diff --git a/src/libslic3r/Extruder.cpp b/src/libslic3r/Extruder.cpp
index 21828e0334..21d101eba0 100644
--- a/src/libslic3r/Extruder.cpp
+++ b/src/libslic3r/Extruder.cpp
@@ -214,7 +214,7 @@ double Extruder::retract_restart_extra_toolchange() const
 
 double Extruder::travel_slope() const
 {
-    return m_config->travel_slope.get_at(m_id) * PI / 180;
+    return m_config->travel_slope.get_at(extruder_id()) * PI / 180;
 }
 
 }
diff --git a/src/libslic3r/FilamentGroup.cpp b/src/libslic3r/FilamentGroup.cpp
index 2a2e6cc0d4..9211385bef 100644
--- a/src/libslic3r/FilamentGroup.cpp
+++ b/src/libslic3r/FilamentGroup.cpp
@@ -36,7 +36,7 @@ namespace Slic3r
             return count;
         };
 
-        uint64_t max_group_num = (1 << m_filament_num);
+        uint64_t max_group_num = static_cast<uint64_t>(1 << m_filament_num);
         int best_cost = std::numeric_limits<int>::max();
         std::vector<int>best_label;
 
@@ -46,7 +46,7 @@ namespace Slic3r
                 continue;
             std::set<int>group_0, group_1;
             for (int j = 0; j < m_filament_num; ++j) {
-                if (i & (1 << j))
+                if (i & static_cast<uint64_t>(1 << j))
                     group_1.insert(m_used_filaments[j]);
                 else
                     group_0.insert(m_used_filaments[j]);
diff --git a/src/libslic3r/GCode.cpp b/src/libslic3r/GCode.cpp
index 7f26ed2bad..80235aa76b 100644
--- a/src/libslic3r/GCode.cpp
+++ b/src/libslic3r/GCode.cpp
@@ -256,7 +256,7 @@ static std::vector<Vec2d> get_path_of_change_filament(const Print& print)
     {
         std::string gcode;
 
-        unsigned int extruder_id = gcodegen.writer().extruder()->id();
+        unsigned int extruder_id = gcodegen.writer().filament()->id();
         const auto& filament_idle_temp = gcodegen.config().idle_temperature;
         if (filament_idle_temp.get_at(extruder_id) == 0) {
             // There is no idle temperature defined in filament settings.
@@ -281,7 +281,7 @@ static std::vector<Vec2d> get_path_of_change_filament(const Print& print)
     std::string OozePrevention::post_toolchange(GCode& gcodegen)
     {
         return (gcodegen.config().standby_temperature_delta.value != 0) ?
-            gcodegen.writer().set_temperature(this->_get_temp(gcodegen), true, gcodegen.writer().extruder()->id()) :
+            gcodegen.writer().set_temperature(this->_get_temp(gcodegen), true, gcodegen.writer().filament()->id()) :
             std::string();
     }
 
@@ -290,9 +290,9 @@ static std::vector<Vec2d> get_path_of_change_filament(const Print& print)
         // First layer temperature should be used when on the first layer (obviously) and when
         // "other layers" is set to zero (which means it should not be used).
         return (gcodegen.layer() == nullptr || gcodegen.layer()->id() == 0
-             || gcodegen.config().nozzle_temperature.get_at(gcodegen.writer().extruder()->id()) == 0)
-            ? gcodegen.config().nozzle_temperature_initial_layer.get_at(gcodegen.writer().extruder()->id())
-            : gcodegen.config().nozzle_temperature.get_at(gcodegen.writer().extruder()->id());
+             || gcodegen.config().nozzle_temperature.get_at(gcodegen.writer().filament()->id()) == 0)
+            ? gcodegen.config().nozzle_temperature_initial_layer.get_at(gcodegen.writer().filament()->id())
+            : gcodegen.config().nozzle_temperature.get_at(gcodegen.writer().filament()->id());
     }
     
     // Orca:
@@ -301,8 +301,8 @@ static std::vector<Vec2d> get_path_of_change_filament(const Print& print)
     Wipe::RetractionValues Wipe::calculateWipeRetractionLengths(GCode& gcodegen, bool toolchange) {
         auto& writer = gcodegen.writer();
         auto& config = gcodegen.config();
-        auto extruder = writer.extruder();
-        auto extruder_id = extruder->id();
+        auto extruder = writer.filament();
+        auto extruder_id = extruder->extruder_id();
         auto last_pos = gcodegen.last_pos();
         
         // Declare & initialize retraction lengths
@@ -369,7 +369,7 @@ static std::vector<Vec2d> get_path_of_change_filament(const Print& print)
                 amount of retraction. In other words, how far do we move in XY at wipe_speed
                 for the time needed to consume retraction_length at retraction_speed?  */
             // BBS
-            double wipe_dist = scale_(gcodegen.config().wipe_distance.get_at(gcodegen.writer().extruder() ->extruder_id()));
+            double wipe_dist = scale_(gcodegen.config().wipe_distance.get_at(gcodegen.writer().filament() ->extruder_id()));
 
             /*  Take the stored wipe path and replace first point with the current actual position
                 (they might be different, for example, in case of loop clipping).  */
@@ -489,12 +489,12 @@ static std::vector<Vec2d> get_path_of_change_filament(const Print& print)
 
         // Process the end filament gcode.
         std::string end_filament_gcode_str;
-        if (gcodegen.writer().extruder() != nullptr) {
+        if (gcodegen.writer().filament() != nullptr) {
             // Process the custom filament_end_gcode in case of single_extruder_multi_material.
-            unsigned int       old_extruder_id    = gcodegen.writer().extruder()->id();
-            const std::string &filament_end_gcode = gcodegen.config().filament_end_gcode.get_at(old_extruder_id);
-            if (gcodegen.writer().extruder() != nullptr && !filament_end_gcode.empty()) {
-                end_filament_gcode_str = gcodegen.placeholder_parser_process("filament_end_gcode", filament_end_gcode, old_extruder_id);
+            unsigned int        old_filament_id = gcodegen.writer().filament()->id();
+            const std::string& filament_end_gcode = gcodegen.config().filament_end_gcode.get_at(old_filament_id);
+            if (gcodegen.writer().filament() != nullptr && !filament_end_gcode.empty()) {
+                end_filament_gcode_str = gcodegen.placeholder_parser_process("filament_end_gcode", filament_end_gcode, old_filament_id);
                 check_add_eol(end_filament_gcode_str);
             }
         }
@@ -512,8 +512,8 @@ static std::vector<Vec2d> get_path_of_change_filament(const Print& print)
         //        m_max_layer_z = std::max(m_max_layer_z, tcr.print_z);
         if (!change_filament_gcode.empty()) {
             DynamicConfig config;
-            int previous_filament_id = gcodegen.writer().extruder() ? (int)gcodegen.writer().extruder()->id() : -1;
-            int previous_extruder_id = gcodegen.writer().extruder() ? (int)gcodegen.writer().extruder()->extruder_id() : -1;
+            int previous_filament_id = gcodegen.writer().filament(new_extruder_id) ? (int)gcodegen.writer().filament(new_extruder_id)->id() : -1;
+            int previous_extruder_id = gcodegen.writer().filament(new_extruder_id) ? (int)gcodegen.writer().filament(new_extruder_id)->extruder_id() : -1;
 
             config.set_key_value("previous_extruder", new ConfigOptionInt(previous_filament_id));
             config.set_key_value("next_extruder", new ConfigOptionInt((int)new_filament_id));
@@ -525,11 +525,11 @@ static std::vector<Vec2d> get_path_of_change_filament(const Print& print)
             {
                 GCodeWriter& gcode_writer = gcodegen.m_writer;
                 FullPrintConfig& full_config = gcodegen.m_config;
-                float old_retract_length = gcode_writer.extruder() != nullptr ? full_config.retraction_length.get_at(previous_extruder_id) : 0;
+                float old_retract_length = gcode_writer.filament(new_extruder_id) != nullptr ? full_config.retraction_length.get_at(previous_filament_id) : 0;
                 float new_retract_length = full_config.retraction_length.get_at(new_extruder_id);
-                float old_retract_length_toolchange = gcode_writer.extruder() != nullptr ? full_config.retract_length_toolchange.get_at(previous_extruder_id) : 0;
+                float old_retract_length_toolchange = gcode_writer.filament(new_extruder_id) != nullptr ? full_config.retract_length_toolchange.get_at(previous_filament_id) : 0;
                 float new_retract_length_toolchange = full_config.retract_length_toolchange.get_at(new_extruder_id);
-                int old_filament_temp = gcode_writer.extruder() != nullptr ? (gcodegen.on_first_layer()? full_config.nozzle_temperature_initial_layer.get_at(previous_filament_id) : full_config.nozzle_temperature.get_at(previous_filament_id)) : 210;
+                int old_filament_temp = gcode_writer.filament(new_extruder_id) != nullptr ? (gcodegen.on_first_layer()? full_config.nozzle_temperature_initial_layer.get_at(previous_filament_id) : full_config.nozzle_temperature.get_at(previous_filament_id)) : 210;
                 int new_filament_temp = gcodegen.on_first_layer() ? full_config.nozzle_temperature_initial_layer.get_at(new_filament_id) : full_config.nozzle_temperature.get_at(new_filament_id);
                 Vec3d nozzle_pos = gcode_writer.get_position();
 
@@ -537,7 +537,7 @@ static std::vector<Vec2d> get_path_of_change_filament(const Print& print)
                 float filament_area = float((M_PI / 4.f) * pow(full_config.filament_diameter.get_at(new_filament_id), 2));
                 float purge_length = purge_volume / filament_area;
 
-                int old_filament_e_feedrate = gcode_writer.extruder() != nullptr ? (int)(60.0 * full_config.filament_max_volumetric_speed.get_at(previous_filament_id) / filament_area) : 200;
+                int old_filament_e_feedrate = gcode_writer.filament(new_extruder_id) != nullptr ? (int)(60.0 * full_config.filament_max_volumetric_speed.get_at(previous_filament_id) / filament_area) : 200;
                 old_filament_e_feedrate = old_filament_e_feedrate == 0 ? 100 : old_filament_e_feedrate;
                 int new_filament_e_feedrate = (int)(60.0 * full_config.filament_max_volumetric_speed.get_at(new_filament_id) / filament_area);
                 new_filament_e_feedrate = new_filament_e_feedrate == 0 ? 100 : new_filament_e_feedrate;
@@ -1011,8 +1011,8 @@ static std::vector<Vec2d> get_path_of_change_filament(const Print& print)
 
     const std::vector<std::string> ColorPrintColors::Colors = { "#C0392B", "#E67E22", "#F1C40F", "#27AE60", "#1ABC9C", "#2980B9", "#9B59B6" };
 
-#define EXTRUDER_CONFIG(OPT) m_config.OPT.get_at(m_writer.extruder()->extruder_id())
-#define FILAMENT_CONFIG(OPT) m_config.OPT.get_at(m_writer.extruder()->id())
+#define EXTRUDER_CONFIG(OPT) m_config.OPT.get_at(m_writer.filament()->extruder_id())
+#define FILAMENT_CONFIG(OPT) m_config.OPT.get_at(m_writer.filament()->id())
 
 void GCode::PlaceholderParserIntegration::reset()
 {
@@ -2652,7 +2652,7 @@ void GCode::_do_export(Print& print, GCodeOutputStream &file, ThumbnailsGenerato
         config.set_key_value("max_layer_z", new ConfigOptionFloat(m_max_layer_z));
         if (print.config().single_extruder_multi_material) {
             // Process the filament_end_gcode for the active filament only.
-            int extruder_id = m_writer.extruder()->id();
+            int extruder_id = m_writer.filament()->id();
             config.set_key_value("filament_extruder_id", new ConfigOptionInt(extruder_id));
             file.writeln(this->placeholder_parser_process("filament_end_gcode", print.config().filament_end_gcode.get_at(extruder_id), extruder_id, &config));
         } else {
@@ -2662,7 +2662,7 @@ void GCode::_do_export(Print& print, GCodeOutputStream &file, ThumbnailsGenerato
                 file.writeln(this->placeholder_parser_process("filament_end_gcode", end_gcode, extruder_id, &config));
             }
         }
-        file.writeln(this->placeholder_parser_process("machine_end_gcode", print.config().machine_end_gcode, m_writer.extruder()->id(), &config));
+        file.writeln(this->placeholder_parser_process("machine_end_gcode", print.config().machine_end_gcode, m_writer.filament()->id(), &config));
     }
     file.write(m_writer.update_progress(m_layer_count, m_layer_count, true)); // 100%
     file.write(m_writer.postamble());
@@ -2949,7 +2949,7 @@ void GCode::process_layers(
     	tbb::parallel_pipeline(12, generator & cooling & fan_mover & pa_processor_filter & output);
 }
 
-std::string GCode::placeholder_parser_process(const std::string &name, const std::string &templ, unsigned int current_extruder_id, const DynamicConfig *config_override)
+std::string GCode::placeholder_parser_process(const std::string &name, const std::string &templ, unsigned int current_filament_id, const DynamicConfig *config_override)
 {
     // Orca: Added CMake config option since debug is rarely used in current workflow.
     // Also changed from throwing error immediately to storing messages till slicing is completed
@@ -2990,7 +2990,7 @@ std::string GCode::placeholder_parser_process(const std::string &name, const std
 PlaceholderParserIntegration &ppi = m_placeholder_parser_integration;
     try {
         ppi.update_from_gcodewriter(m_writer);
-        std::string output = ppi.parser.process(templ, current_extruder_id, config_override, &ppi.output_config, &ppi.context);
+        std::string output = ppi.parser.process(templ, current_filament_id, config_override, &ppi.output_config, &ppi.context);
         ppi.validate_output_vector_variables();
 
         if (const std::vector<double> &pos = ppi.opt_position->values; ppi.position != pos) {
@@ -3691,7 +3691,7 @@ LayerResult GCode::process_layer(
         config.set_key_value("layer_z",     new ConfigOptionFloat(print_z));
         config.set_key_value("max_layer_z", new ConfigOptionFloat(m_max_layer_z));
         gcode += this->placeholder_parser_process("before_layer_change_gcode",
-            print.config().before_layer_change_gcode.value, m_writer.extruder()->id(), &config)
+            print.config().before_layer_change_gcode.value, m_writer.filament()->id(), &config)
             + "\n";
     }
 
@@ -3713,7 +3713,7 @@ LayerResult GCode::process_layer(
             config.set_key_value("layer_num", new ConfigOptionInt(m_layer_index));
             config.set_key_value("layer_z", new ConfigOptionFloat(print_z));
             config.set_key_value("max_layer_z", new ConfigOptionFloat(m_max_layer_z));
-            gcode_res = this->placeholder_parser_process("timelapse_gcode", print.config().time_lapse_gcode.value, m_writer.extruder()->id(), &config) + "\n";
+            gcode_res = this->placeholder_parser_process("timelapse_gcode", print.config().time_lapse_gcode.value, m_writer.filament()->id(), &config) + "\n";
         }
         return gcode_res;
     };
@@ -3743,7 +3743,7 @@ LayerResult GCode::process_layer(
             config.set_key_value("layer_num", new ConfigOptionInt(m_layer_index));
             config.set_key_value("layer_z", new ConfigOptionFloat(print_z));
             config.set_key_value("max_layer_z", new ConfigOptionFloat(m_max_layer_z));
-            gcode += this->placeholder_parser_process("timelapse_gcode", print.config().time_lapse_gcode.value, m_writer.extruder()->id(),
+            gcode += this->placeholder_parser_process("timelapse_gcode", print.config().time_lapse_gcode.value, m_writer.filament()->id(),
                                                       &config) +
                      "\n";
         }
@@ -3753,7 +3753,7 @@ LayerResult GCode::process_layer(
         config.set_key_value("layer_num", new ConfigOptionInt(m_layer_index));
         config.set_key_value("layer_z",   new ConfigOptionFloat(print_z));
         gcode += this->placeholder_parser_process("layer_change_gcode",
-            print.config().layer_change_gcode.value, m_writer.extruder()->id(), &config)
+            print.config().layer_change_gcode.value, m_writer.filament()->id(), &config)
             + "\n";
         config.set_key_value("max_layer_z", new ConfigOptionFloat(m_max_layer_z));
     }
@@ -3864,7 +3864,7 @@ LayerResult GCode::process_layer(
         // nozzle_temperature_initial_layer vs. temperature settings.
         for (const Extruder &extruder : m_writer.extruders()) {
             if ((print.config().single_extruder_multi_material.value || m_ooze_prevention.enable) &&
-                extruder.id() != m_writer.extruder()->id())
+                extruder.id() != m_writer.filament()->id())
                 // In single extruder multi material mode, set the temperature for the current extruder only.
                 continue;
             int temperature = print.config().nozzle_temperature.get_at(extruder.id());
@@ -3881,7 +3881,7 @@ LayerResult GCode::process_layer(
 
     if (single_object_instance_idx == size_t(-1)) {
         // Normal (non-sequential) print.
-        gcode += ProcessLayer::emit_custom_gcode_per_print_z(*this, layer_tools.custom_gcode, m_writer.extruder()->id(), first_extruder_id, print.config());
+        gcode += ProcessLayer::emit_custom_gcode_per_print_z(*this, layer_tools.custom_gcode, m_writer.filament()->id(), first_extruder_id, print.config());
     }
 
     // BBS: get next extruder according to flush and soluble
@@ -5306,7 +5306,7 @@ std::string GCode::_extrude(const ExtrusionPath &path, std::string description,
         _mm3_per_mm *= m_config.scarf_joint_flow_ratio;
     // Effective extrusion length per distance unit = (filament_flow_ratio/cross_section) * mm3_per_mm / print flow ratio
     // m_writer.extruder()->e_per_mm3() below is (filament flow ratio / cross-sectional area)
-    double e_per_mm = m_writer.extruder()->e_per_mm3() * _mm3_per_mm;
+    double e_per_mm = m_writer.filament()->e_per_mm3() * _mm3_per_mm;
     e_per_mm /= filament_flow_ratio;
 
 
@@ -5522,7 +5522,7 @@ std::string GCode::_extrude(const ExtrusionPath &path, std::string description,
             config.set_key_value("layer_num", new ConfigOptionInt(m_layer_index + 1));
             config.set_key_value("layer_z", new ConfigOptionFloat(m_layer == nullptr ? m_last_height : m_layer->print_z));
             gcode += this->placeholder_parser_process("change_extrusion_role_gcode",
-                                                      m_config.change_extrusion_role_gcode.value, m_writer.extruder()->id(), &config)
+                                                      m_config.change_extrusion_role_gcode.value, m_writer.filament()->id(), &config)
                      + "\n";
     }
 
@@ -5585,7 +5585,7 @@ std::string GCode::_extrude(const ExtrusionPath &path, std::string description,
         if (m_multi_flow_segment_path_average_mm3_per_mm > 0) {
             sprintf(buf, ";%sT%u MM3MM:%g ACCEL:%u BR:%d RC:%d OV:%d\n",
                     GCodeProcessor::reserved_tag(GCodeProcessor::ETags::PA_Change).c_str(),
-                    m_writer.extruder()->id(),
+                    m_writer.filament()->id(),
                     m_multi_flow_segment_path_average_mm3_per_mm,
                     acceleration_i,
                     ((path.role() == erBridgeInfill) ||(path.role() == erOverhangPerimeter)),
@@ -5598,7 +5598,7 @@ std::string GCode::_extrude(const ExtrusionPath &path, std::string description,
                                     // to issue a zero flow PA change command for this
             sprintf(buf, ";%sT%u MM3MM:%g ACCEL:%u BR:%d RC:%d OV:%d\n",
                     GCodeProcessor::reserved_tag(GCodeProcessor::ETags::PA_Change).c_str(),
-                    m_writer.extruder()->id(),
+                    m_writer.filament()->id(),
                     _mm3_per_mm,
                     acceleration_i,
                     ((path.role() == erBridgeInfill) ||(path.role() == erOverhangPerimeter)),
@@ -5704,7 +5704,7 @@ std::string GCode::_extrude(const ExtrusionPath &path, std::string description,
                     }
                     sprintf(buf, ";%sT%u MM3MM:%g ACCEL:%u BR:%d RC:%d OV:%d\n",
                             GCodeProcessor::reserved_tag(GCodeProcessor::ETags::PA_Change).c_str(),
-                            m_writer.extruder()->id(),
+                            m_writer.filament()->id(),
                             _mm3_per_mm,
                             acceleration_i,
                             ((path.role() == erBridgeInfill) ||(path.role() == erOverhangPerimeter)),
@@ -5719,7 +5719,7 @@ std::string GCode::_extrude(const ExtrusionPath &path, std::string description,
                     }
                     sprintf(buf, ";%sT%u MM3MM:%g ACCEL:%u BR:%d RC:%d OV:%d\n",
                             GCodeProcessor::reserved_tag(GCodeProcessor::ETags::PA_Change).c_str(),
-                            m_writer.extruder()->id(),
+                            m_writer.filament()->id(),
                             _mm3_per_mm,
                             acceleration_i,
                             ((path.role() == erBridgeInfill) ||(path.role() == erOverhangPerimeter)),
@@ -5912,7 +5912,7 @@ std::string GCode::_extrude(const ExtrusionPath &path, std::string description,
                         }
                         sprintf(buf, ";%sT%u MM3MM:%g ACCEL:%u BR:%d RC:%d OV:%d\n",
                                 GCodeProcessor::reserved_tag(GCodeProcessor::ETags::PA_Change).c_str(),
-                                m_writer.extruder()->id(),
+                                m_writer.filament()->id(),
                                 _mm3_per_mm,
                                 acceleration_i,
                                 ((path.role() == erBridgeInfill) ||(path.role() == erOverhangPerimeter)),
@@ -5927,7 +5927,7 @@ std::string GCode::_extrude(const ExtrusionPath &path, std::string description,
                         }
                         sprintf(buf, ";%sT%u MM3MM:%g ACCEL:%u BR:%d RC:%d OV:%d\n",
                                 GCodeProcessor::reserved_tag(GCodeProcessor::ETags::PA_Change).c_str(),
-                                m_writer.extruder()->id(),
+                                m_writer.filament()->id(),
                                 _mm3_per_mm,
                                 acceleration_i,
                                 ((path.role() == erBridgeInfill) ||(path.role() == erOverhangPerimeter)),
@@ -6267,7 +6267,7 @@ bool GCode::needs_retraction(const Polyline &travel, ExtrusionRole role, LiftTyp
     float max_z_hop = 0.f;
     for (int i = 0; i < m_config.z_hop.size(); i++)
         max_z_hop = std::max(max_z_hop, (float)m_config.z_hop.get_at(i));
-    float travel_len_thresh = scale_(max_z_hop / tan(this->writer().extruder()->travel_slope()));
+    float travel_len_thresh = scale_(max_z_hop / tan(this->writer().filament()->travel_slope()));
     float accum_len = 0.f;
     Polyline clipped_travel;
 
@@ -6327,7 +6327,7 @@ std::string GCode::retract(bool toolchange, bool is_last_retraction, LiftType li
 {
     std::string gcode;
 
-    if (m_writer.extruder() == nullptr)
+    if (m_writer.filament() == nullptr)
         return gcode;
 
     // wipe (if it's enabled for this extruder and we have a stored wipe path and no-zero wipe distance)
@@ -6350,7 +6350,7 @@ std::string GCode::retract(bool toolchange, bool is_last_retraction, LiftType li
     RetractLiftEnforceType retract_lift_type = RetractLiftEnforceType(EXTRUDER_CONFIG(retract_lift_enforce));
 
     bool needs_lift = toolchange
-        || m_writer.extruder()->retraction_length() > 0
+        || m_writer.filament()->retraction_length() > 0
         || m_config.use_firmware_retraction;
 
     bool last_fill_extrusion_role_top_infill = (this->m_last_notgapfill_extrusion_role == ExtrusionRole::erTopSolidInfill || this->m_last_notgapfill_extrusion_role == ExtrusionRole::erIroning);
@@ -6429,18 +6429,18 @@ std::string GCode::set_extruder(unsigned int filament_id, double print_z, bool b
     if (by_object)
         m_writer.add_object_change_labels(gcode);
 
-    if (m_writer.extruder() != nullptr) {
+    if (m_writer.filament() != nullptr) {
         // Process the custom filament_end_gcode. set_extruder() is only called if there is no wipe tower
         // so it should not be injected twice.
-        unsigned int        old_extruder_id     = m_writer.extruder()->id();
-        const std::string  &filament_end_gcode  = m_config.filament_end_gcode.get_at(old_extruder_id);
+        unsigned int        old_filament_id = m_writer.filament()->id();
+        const std::string  &filament_end_gcode  = m_config.filament_end_gcode.get_at(old_filament_id);
         if (! filament_end_gcode.empty()) {
             DynamicConfig config;
             config.set_key_value("layer_num", new ConfigOptionInt(m_layer_index));
             config.set_key_value("layer_z",   new ConfigOptionFloat(m_writer.get_position().z() - m_config.z_offset.value));
             config.set_key_value("max_layer_z", new ConfigOptionFloat(m_max_layer_z));
-            config.set_key_value("filament_extruder_id", new ConfigOptionInt(int(old_extruder_id)));
-            gcode += placeholder_parser_process("filament_end_gcode", filament_end_gcode, old_extruder_id, &config);
+            config.set_key_value("filament_extruder_id", new ConfigOptionInt(int(get_extruder_id(old_filament_id))));
+            gcode += placeholder_parser_process("filament_end_gcode", filament_end_gcode, old_filament_id, &config);
             check_add_eol(gcode);
         }
     }
@@ -6448,7 +6448,7 @@ std::string GCode::set_extruder(unsigned int filament_id, double print_z, bool b
 
     // If ooze prevention is enabled, park current extruder in the nearest
     // standby point and set it to the standby temperature.
-    if (m_ooze_prevention.enable && m_writer.extruder() != nullptr)
+    if (m_ooze_prevention.enable && m_writer.filament() != nullptr)
         gcode += m_ooze_prevention.pre_toolchange(*this);
 
     // BBS
@@ -6466,23 +6466,34 @@ std::string GCode::set_extruder(unsigned int filament_id, double print_z, bool b
     float filament_area = float((M_PI / 4.f) * pow(m_config.filament_diameter.get_at(filament_id), 2));
     //BBS: add handling for filament change in start gcode
     int previous_filament_id = -1;
-    if (m_writer.extruder() != nullptr || m_start_gcode_filament != -1) {
-        std::vector<float> flush_matrix(cast<float>(get_flush_volumes_matrix(m_config.flush_volumes_matrix.values, 0, m_config.nozzle_diameter.values.size())));
+    if (m_writer.filament() != nullptr || m_start_gcode_filament != -1) {
+        std::vector<float> flush_matrix(cast<float>(get_flush_volumes_matrix(m_config.flush_volumes_matrix.values, extruder_id, m_config.nozzle_diameter.values.size())));
         const unsigned int number_of_extruders = (unsigned int) (m_config.filament_colour.values.size()); // if is multi_extruder only use the fist extruder matrix
-        if (m_writer.extruder() != nullptr)
-            assert(m_writer.extruder()->id() < number_of_extruders);
+        if (m_writer.filament() != nullptr)
+            assert(m_writer.filament()->id() < number_of_extruders);
         else
             assert(m_start_gcode_filament < number_of_extruders);
 
-        previous_filament_id = m_writer.extruder() != nullptr ? m_writer.extruder()->id() : m_start_gcode_filament;
-        int previous_extruder_id = m_writer.extruder() != nullptr ? m_writer.extruder()->extruder_id() : m_start_gcode_filament;
+        previous_filament_id = m_writer.filament() != nullptr ? m_writer.filament()->id() : m_start_gcode_filament;
+        int previous_extruder_id = m_writer.filament() != nullptr ? m_writer.filament()->extruder_id() : get_extruder_id(m_start_gcode_filament);
 
         old_retract_length = m_config.retraction_length.get_at(previous_extruder_id);
         old_retract_length_toolchange = m_config.retract_length_toolchange.get_at(previous_extruder_id);
         old_filament_temp = this->on_first_layer()? m_config.nozzle_temperature_initial_layer.get_at(previous_filament_id) : m_config.nozzle_temperature.get_at(previous_filament_id);
-        //Orca: always calculate wipe volume and hence provide correct flush_length, so that MMU devices with cutter and purge bin (e.g. ERCF_v2 with a filament cutter or Filametrix can take advantage of it)
-        wipe_volume = flush_matrix[previous_filament_id * number_of_extruders + filament_id];
-        wipe_volume *= m_config.flush_multiplier.get_at(0);  // if is multi_extruder only use the fist extruder matrix
+        if (previous_extruder_id != extruder_id) {
+            //calc flush volume between the same extruder id
+            int previous_filament_id_in_new_extruder = m_writer.filament(extruder_id) != nullptr ? m_writer.filament(extruder_id)->id() : -1;
+            if (previous_filament_id_in_new_extruder == -1)
+                wipe_volume = 0;
+            else {
+                wipe_volume = flush_matrix[previous_filament_id_in_new_extruder * number_of_extruders + filament_id];
+                wipe_volume *= m_config.flush_multiplier.get_at(extruder_id);
+            }
+        }
+        else {
+            wipe_volume = flush_matrix[previous_filament_id * number_of_extruders + filament_id];
+            wipe_volume *= m_config.flush_multiplier.get_at(extruder_id);  // if is multi_extruder only use the fist extruder matrix
+        }
 
         old_filament_e_feedrate = (int) (60.0 * m_config.filament_max_volumetric_speed.get_at(previous_filament_id) / filament_area);
         old_filament_e_feedrate = old_filament_e_feedrate == 0 ? 100 : old_filament_e_feedrate;
@@ -6699,9 +6710,9 @@ Vec2d GCode::point_to_gcode(const Point &point) const
 Point GCode::gcode_to_point(const Vec2d &point) const
 {
     Vec2d pt = point - m_origin;
-    if (const Extruder *extruder = m_writer.extruder(); extruder)
+    if (const Extruder *extruder = m_writer.filament(); extruder)
         // This function may be called at the very start from toolchange G-code when the extruder is not assigned yet.
-        pt += m_config.extruder_offset.get_at(extruder->id());
+        pt += m_config.extruder_offset.get_at(extruder->extruder_id());
     return scaled<coord_t>(pt);
         
 }
diff --git a/src/libslic3r/GCode.hpp b/src/libslic3r/GCode.hpp
index 8490e793a4..02df4b7796 100644
--- a/src/libslic3r/GCode.hpp
+++ b/src/libslic3r/GCode.hpp
@@ -214,7 +214,7 @@ public:
     const PlaceholderParser& placeholder_parser() const { return m_placeholder_parser_integration.parser; }
     // Process a template through the placeholder parser, collect error messages to be reported
     // inside the generated string and after the G-code export finishes.
-    std::string     placeholder_parser_process(const std::string &name, const std::string &templ, unsigned int current_extruder_id, const DynamicConfig *config_override = nullptr);
+    std::string     placeholder_parser_process(const std::string &name, const std::string &templ, unsigned int current_filament_id, const DynamicConfig *config_override = nullptr);
     bool            enable_cooling_markers() const { return m_enable_cooling_markers; }
     std::string     extrusion_role_to_string_for_parser(const ExtrusionRole &);
 
diff --git a/src/libslic3r/GCode/AvoidCrossingPerimeters.cpp b/src/libslic3r/GCode/AvoidCrossingPerimeters.cpp
index fd65411667..3aef4fab18 100644
--- a/src/libslic3r/GCode/AvoidCrossingPerimeters.cpp
+++ b/src/libslic3r/GCode/AvoidCrossingPerimeters.cpp
@@ -773,7 +773,7 @@ static bool need_wipe(const GCode                    &gcodegen,
                       const Polyline                 &result_travel,
                       const size_t                    intersection_count)
 {
-    bool z_lift_enabled = gcodegen.config().z_hop.get_at(gcodegen.writer().extruder()->extruder_id()) > 0.;
+    bool z_lift_enabled = gcodegen.config().z_hop.get_at(gcodegen.writer().filament()->id()) > 0.;
     bool wipe_needed    = false;
 
     // If the original unmodified path doesn't have any intersection with boundary, then it is entirely inside the object otherwise is entirely
diff --git a/src/libslic3r/GCode/ToolOrdering.hpp b/src/libslic3r/GCode/ToolOrdering.hpp
index 4c31d5175c..45c5d30515 100644
--- a/src/libslic3r/GCode/ToolOrdering.hpp
+++ b/src/libslic3r/GCode/ToolOrdering.hpp
@@ -8,7 +8,7 @@
 #include <utility>
 
 #include <boost/container/small_vector.hpp>
-#include "FilamentGroup.hpp"
+#include "../FilamentGroup.hpp"
 #include "ExtrusionEntity.hpp"
 #include "PrintConfig.hpp"
 
diff --git a/src/libslic3r/GCodeWriter.cpp b/src/libslic3r/GCodeWriter.cpp
index c0b8891f75..32dc859403 100644
--- a/src/libslic3r/GCodeWriter.cpp
+++ b/src/libslic3r/GCodeWriter.cpp
@@ -46,11 +46,10 @@ void GCodeWriter::apply_print_config(const PrintConfig &print_config)
 void GCodeWriter::set_extruders(std::vector<unsigned int> extruder_ids)
 {
     std::sort(extruder_ids.begin(), extruder_ids.end());
-    m_extruder = nullptr; // this points to object inside `m_extruders`, so should be cleared too
-    m_extruders.clear();
-    m_extruders.reserve(extruder_ids.size());
+    m_filament_extruders.clear();
+    m_filament_extruders.reserve(extruder_ids.size());
     for (unsigned int extruder_id : extruder_ids)
-        m_extruders.emplace_back(Extruder(extruder_id, &this->config, config.single_extruder_multi_material.value));
+        m_filament_extruders.emplace_back(Extruder(extruder_id, &this->config, config.single_extruder_multi_material.value));
 
     /*  we enable support for multiple extruder if any extruder greater than 0 is used
         (even if prints only uses that one) since we need to output Tx commands
@@ -407,10 +406,10 @@ std::string GCodeWriter::reset_e(bool force)
         || FLAVOR_IS(gcfSailfish))
         return "";
 
-    if (m_extruder != nullptr) {
-        if (is_zero(m_extruder->E()) && ! force)
+    if (m_curr_extruder_id!=-1 && m_curr_filament_extruder[m_curr_extruder_id] != nullptr) {
+        if (is_zero(m_curr_filament_extruder[m_curr_extruder_id]->E()) && ! force)
             return "";
-        m_extruder->reset_E();
+        m_curr_filament_extruder[m_curr_extruder_id]->reset_E();
     }
 
     if (! this->config.use_relative_e_distances) {
@@ -452,12 +451,13 @@ std::string GCodeWriter::toolchange_prefix() const
            FLAVOR_IS(gcfSailfish)  ? "M108 T" : "T";
 }
 
-std::string GCodeWriter::toolchange(unsigned int extruder_id)
+std::string GCodeWriter::toolchange(unsigned int filament_id)
 {
     // set the new extruder
-	auto it_extruder = Slic3r::lower_bound_by_predicate(m_extruders.begin(), m_extruders.end(), [extruder_id](const Extruder &e) { return e.id() < extruder_id; });
-    assert(it_extruder != m_extruders.end() && it_extruder->id() == extruder_id);
-    m_extruder = &*it_extruder;
+    auto filament_extruder_iter = Slic3r::lower_bound_by_predicate(m_filament_extruders.begin(), m_filament_extruders.end(), [filament_id](const Extruder &e) { return e.id() < filament_id; });
+    assert(filament_extruder_iter != m_filament_extruders.end() && filament_extruder_iter->id() == filament_id);
+    m_curr_extruder_id = filament_extruder_iter->extruder_id();
+    m_curr_filament_extruder[m_curr_extruder_id] = &*filament_extruder_iter;
 
     // return the toolchange command
     // if we are running a single-extruder setup, just set the extruder and return nothing
@@ -465,9 +465,9 @@ std::string GCodeWriter::toolchange(unsigned int extruder_id)
     if (this->multiple_extruders || (this->config.filament_diameter.values.size() > 1 && !is_bbl_printers())) {
         // BBS
         if (this->m_is_bbl_printers)
-            gcode << "M1020 S" << extruder_id;
+            gcode << "M1020 S" << filament_id;
         else
-            gcode << this->toolchange_prefix() << extruder_id;
+            gcode << this->toolchange_prefix() << filament_id;
         //BBS
         if (GCodeWriter::full_gcode_comment)
             gcode << " ; change extruder";
@@ -550,7 +550,7 @@ std::string GCodeWriter::travel_to_xyz(const Vec3d &point, const std::string &co
             //BBS: SpiralLift
             if (m_to_lift_type == LiftType::SpiralLift && this->is_current_position_clear()) {
                 //BBS: todo: check the arc move all in bed area, if not, then use lazy lift
-                double radius = delta(2) / (2 * PI * atan(this->extruder()->travel_slope()));
+                double radius = delta(2) / (2 * PI * atan(this->filament()->travel_slope()));
                 Vec2d ij_offset = radius * delta_no_z.normalized();
                 ij_offset = { -ij_offset(1), ij_offset(0) };
                 slop_move = this->_spiral_travel_to_z(target(2), ij_offset, "spiral lift Z");
@@ -558,11 +558,11 @@ std::string GCodeWriter::travel_to_xyz(const Vec3d &point, const std::string &co
             //BBS: LazyLift
             else if (m_to_lift_type == LiftType::LazyLift &&
                 this->is_current_position_clear() &&
-                atan2(delta(2), delta_no_z.norm()) < this->extruder()->travel_slope()) {
+                atan2(delta(2), delta_no_z.norm()) < this->filament()->travel_slope()) {
                 //BBS: check whether we can make a travel like
                 //   _____
                 //  /       to make the z list early to avoid to hit some warping place when travel is long.
-                Vec2d temp = delta_no_z.normalized() * delta(2) / tan(this->extruder()->travel_slope());
+                Vec2d temp = delta_no_z.normalized() * delta(2) / tan(this->filament()->travel_slope());
                 Vec3d slope_top_point = Vec3d(temp(0), temp(1), delta(2)) + source;
                 GCodeG1Formatter w0;
                 w0.emit_xyz(slope_top_point);
@@ -719,7 +719,7 @@ std::string GCodeWriter::extrude_to_xy(const Vec2d &point, double dE, const std:
         force_no_extrusion = true;
 
     if (!force_no_extrusion)
-        m_extruder->extrude(dE);
+        filament()->extrude(dE);
 
     //BBS: take plate offset into consider
     Vec2d point_on_plate = { point(0) - m_x_offset, point(1) - m_y_offset };
@@ -727,7 +727,7 @@ std::string GCodeWriter::extrude_to_xy(const Vec2d &point, double dE, const std:
     GCodeG1Formatter w;
     w.emit_xy(point_on_plate);
     if (!force_no_extrusion)
-        w.emit_e(m_extruder->E());
+        w.emit_e(filament()->E());
     //BBS
     w.emit_comment(GCodeWriter::full_gcode_comment, comment);
     return w.string();
@@ -741,7 +741,7 @@ std::string GCodeWriter::extrude_arc_to_xy(const Vec2d& point, const Vec2d& cent
     m_pos(0) = point(0);
     m_pos(1) = point(1);
     if (!force_no_extrusion)
-        m_extruder->extrude(dE);
+        filament()->extrude(dE);
 
     Vec2d point_on_plate = { point(0) - m_x_offset, point(1) - m_y_offset };
 
@@ -749,7 +749,7 @@ std::string GCodeWriter::extrude_arc_to_xy(const Vec2d& point, const Vec2d& cent
     w.emit_xy(point_on_plate);
     w.emit_ij(center_offset);
     if (!force_no_extrusion)
-        w.emit_e(m_extruder->E());
+        w.emit_e(filament()->E());
     //BBS
     w.emit_comment(GCodeWriter::full_gcode_comment, comment);
     return w.string();
@@ -760,7 +760,7 @@ std::string GCodeWriter::extrude_to_xyz(const Vec3d &point, double dE, const std
     m_pos = point;
     m_lifted = 0;
     if (!force_no_extrusion)
-        m_extruder->extrude(dE);
+        filament()->extrude(dE);
 
     //BBS: take plate offset into consider
     Vec3d point_on_plate = { point(0) - m_x_offset, point(1) - m_y_offset, point(2) };
@@ -768,7 +768,7 @@ std::string GCodeWriter::extrude_to_xyz(const Vec3d &point, double dE, const std
     GCodeG1Formatter w;
     w.emit_xyz(point_on_plate);
     if (!force_no_extrusion)
-        w.emit_e(m_extruder->E());
+        w.emit_e(filament()->E());
     //BBS
     w.emit_comment(GCodeWriter::full_gcode_comment, comment);
     return w.string();
@@ -776,22 +776,22 @@ std::string GCodeWriter::extrude_to_xyz(const Vec3d &point, double dE, const std
 
 std::string GCodeWriter::retract(bool before_wipe, double retract_length)
 {
-    double factor = before_wipe ? m_extruder->retract_before_wipe() : 1.;
+    double factor = before_wipe ? filament()->retract_before_wipe() : 1.;
     assert(factor >= 0. && factor <= 1. + EPSILON);
     return this->_retract(
-        retract_length > EPSILON ? retract_length : factor * m_extruder->retraction_length(),
-        factor * m_extruder->retract_restart_extra(),
+        retract_length > EPSILON ? retract_length : factor * filament()->retraction_length(),
+        factor * filament()->retract_restart_extra(),
         "retract"
     );
 }
 
 std::string GCodeWriter::retract_for_toolchange(bool before_wipe, double retract_length)
 {
-    double factor = before_wipe ? m_extruder->retract_before_wipe() : 1.;
+    double factor = before_wipe ? filament()->retract_before_wipe() : 1.;
     assert(factor >= 0. && factor <= 1. + EPSILON);
     return this->_retract(
-        retract_length > EPSILON ? retract_length : factor * m_extruder->retract_length_toolchange(),
-        factor * m_extruder->retract_restart_extra_toolchange(),
+        retract_length > EPSILON ? retract_length : factor * filament()->retract_length_toolchange(),
+        factor * filament()->retract_restart_extra_toolchange(),
         "retract for toolchange"
     );
 }
@@ -805,15 +805,15 @@ std::string GCodeWriter::_retract(double length, double restart_extra, const std
         length = 1;
 
     std::string gcode;
-    if (double dE = m_extruder->retract(length, restart_extra);  !is_zero(dE)) {
+    if (double dE = filament()->retract(length, restart_extra);  !is_zero(dE)) {
         if (this->config.use_firmware_retraction) {
             gcode = FLAVOR_IS(gcfMachinekit) ? "G22 ; retract\n" : "G10 ; retract\n";
         }
         else {
             // BBS
             GCodeG1Formatter w;
-            w.emit_e(m_extruder->E());
-            w.emit_f(m_extruder->retract_speed() * 60.);
+            w.emit_e(filament()->E());
+            w.emit_f(filament()->retract_speed() * 60.);
             // BBS
             w.emit_comment(GCodeWriter::full_gcode_comment, comment);
             gcode = w.string();
@@ -833,7 +833,7 @@ std::string GCodeWriter::unretract()
     if (FLAVOR_IS(gcfMakerWare))
         gcode = "M101 ; extruder on\n";
 
-    if (double dE = m_extruder->unretract(); !is_zero(dE)) {
+    if (double dE = filament()->unretract(); !is_zero(dE)) {
         if (this->config.use_firmware_retraction) {
             gcode += FLAVOR_IS(gcfMachinekit) ? "G23 ; unretract\n" : "G11 ; unretract\n";
             gcode += this->reset_e();
@@ -842,8 +842,8 @@ std::string GCodeWriter::unretract()
             //BBS
             // use G1 instead of G0 because G0 will blend the restart with the previous travel move
             GCodeG1Formatter w;
-            w.emit_e(m_extruder->E());
-            w.emit_f(m_extruder->deretract_speed() * 60.);
+            w.emit_e(filament()->E());
+            w.emit_f(filament()->deretract_speed() * 60.);
             //BBS
             w.emit_comment(GCodeWriter::full_gcode_comment, " ; unretract");
             gcode += w.string();
@@ -861,7 +861,7 @@ std::string GCodeWriter::lift(LiftType lift_type, bool spiral_vase)
     // check whether the above/below conditions are met
     double target_lift = 0;
     {
-        int extruder_id = m_extruder->extruder_id();
+        int extruder_id = filament()->extruder_id();
         double above = this->config.retract_lift_above.get_at(extruder_id);
         double below = this->config.retract_lift_below.get_at(extruder_id);
         if (m_pos(2) >= above && (below == 0 || m_pos(2) <= below))
@@ -985,6 +985,21 @@ void GCodeWriter::add_object_change_labels(std::string& gcode)
     add_object_start_labels(gcode);
 }
 
+std::string GCodeWriter::set_extruder(unsigned int filament_id)
+{
+    auto filament_ext_it = Slic3r::lower_bound_by_predicate(m_filament_extruders.begin(), m_filament_extruders.end(), [filament_id](const Extruder &e) { return e.id() < filament_id; });
+    unsigned int extruder_id = filament_ext_it->extruder_id();
+    assert(filament_ext_it != m_filament_extruders.end() && filament_ext_it->id() == filament_id);
+    //TODO: optmize here, pass extruder_id to toolchange
+    return this->need_toolchange(filament_id) ? this->toolchange(filament_id) : "";
+}
+
+
+bool GCodeWriter::need_toolchange(unsigned int filament_id)const
+{
+    return filament()==nullptr || filament()->id()!=filament_id;
+}
+
 void GCodeFormatter::emit_axis(const char axis, const double v, size_t digits) {
     assert(digits <= 9);
     static constexpr const std::array<int, 10> pow_10{1, 10, 100, 1000, 10000, 100000, 1000000, 10000000, 100000000, 1000000000};
diff --git a/src/libslic3r/GCodeWriter.hpp b/src/libslic3r/GCodeWriter.hpp
index e4eacd22d6..0fa7fad4ee 100644
--- a/src/libslic3r/GCodeWriter.hpp
+++ b/src/libslic3r/GCodeWriter.hpp
@@ -15,9 +15,10 @@ class GCodeWriter {
 public:
     GCodeConfig config;
     bool multiple_extruders;
-    
-    GCodeWriter() : 
-        multiple_extruders(false), m_extruder(nullptr),
+
+    GCodeWriter() :
+        multiple_extruders(false), m_curr_filament_extruder{ nullptr,nullptr },
+        m_curr_extruder_id (-1),
         m_single_extruder_multi_material(false),
         m_last_acceleration(0), m_max_acceleration(0),m_last_travel_acceleration(0), m_max_travel_acceleration(0),
         m_last_jerk(0), m_max_jerk_x(0), m_max_jerk_y(0),
@@ -27,18 +28,20 @@ public:
         m_to_lift_type(LiftType::NormalLift),
         m_current_speed(3600), m_is_first_layer(true)
         {}
-    Extruder*            extruder()             { return m_extruder; }
-    const Extruder*      extruder()     const   { return m_extruder; }
+    Extruder* filament(size_t extruder_id) { assert(extruder_id < m_curr_filament_extruder.size()); return m_curr_filament_extruder[extruder_id]; }
+    const Extruder* filament(size_t extruder_id) const { assert(extruder_id < m_curr_filament_extruder.size()); return m_curr_filament_extruder[extruder_id]; }
+    Extruder* filament() { if (m_curr_extruder_id == -1) return nullptr; return m_curr_filament_extruder[m_curr_extruder_id]; }
+    const Extruder* filament() const { if(m_curr_extruder_id==-1) return nullptr; return m_curr_filament_extruder[m_curr_extruder_id]; }
 
     void                 apply_print_config(const PrintConfig &print_config);
     // Extruders are expected to be sorted in an increasing order.
     void                 set_extruders(std::vector<unsigned int> extruder_ids);
-    const std::vector<Extruder>& extruders() const { return m_extruders; }
-    std::vector<unsigned int> extruder_ids() const { 
-        std::vector<unsigned int> out; 
-        out.reserve(m_extruders.size()); 
-        for (const Extruder &e : m_extruders) 
-            out.push_back(e.id()); 
+    const std::vector<Extruder>& extruders() const { return m_filament_extruders; }
+    std::vector<unsigned int> extruder_ids() const {
+        std::vector<unsigned int> out;
+        out.reserve(m_filament_extruders.size());
+        for (const Extruder &e : m_filament_extruders)
+            out.push_back(e.id());
         return out;
     }
     std::string preamble();
@@ -59,14 +62,12 @@ public:
     std::string reset_e(bool force = false);
     std::string update_progress(unsigned int num, unsigned int tot, bool allow_100 = false) const;
     // return false if this extruder was already selected
-    bool        need_toolchange(unsigned int extruder_id) const 
-        { return m_extruder == nullptr || m_extruder->id() != extruder_id; }
-    std::string set_extruder(unsigned int extruder_id)
-        { return this->need_toolchange(extruder_id) ? this->toolchange(extruder_id) : ""; }
+    bool        need_toolchange(unsigned int filament_id) const;
+    std::string set_extruder(unsigned int filament_id);
     // Prefix of the toolchange G-code line, to be used by the CoolingBuffer to separate sections of the G-code
     // printed with the same extruder.
     std::string toolchange_prefix() const;
-    std::string toolchange(unsigned int extruder_id);
+    std::string toolchange(unsigned int filament_id);
     std::string set_speed(double F, const std::string &comment = std::string(), const std::string &cooling_marker = std::string());
     // SoftFever NOTE: the returned speed is mm/minute
     double      get_current_speed() const { return m_current_speed;}
@@ -123,9 +124,10 @@ public:
     static bool supports_separate_travel_acceleration(GCodeFlavor flavor);
   private:
 	// Extruders are sorted by their ID, so that binary search is possible.
-    std::vector<Extruder> m_extruders;
+    std::vector<Extruder> m_filament_extruders;
     bool            m_single_extruder_multi_material;
-    Extruder*       m_extruder;
+    std::vector<Extruder*> m_curr_filament_extruder;
+    int        m_curr_extruder_id;
     unsigned int    m_last_acceleration;
     unsigned int    m_last_travel_acceleration;
     unsigned int    m_max_travel_acceleration;
diff --git a/src/libslic3r/Print.cpp b/src/libslic3r/Print.cpp
index e26dc48587..0716feb221 100644
--- a/src/libslic3r/Print.cpp
+++ b/src/libslic3r/Print.cpp
@@ -2769,14 +2769,7 @@ void Print::_make_wipe_tower()
                 multi_extruder_flush.emplace_back(wipe_volumes);
             }
 
-            // todo multi_extruders: get filament_maps
-            std::vector<int> filament_maps;
-            for (int i = 0; i <= number_of_extruders / 2; ++i) {
-                filament_maps.push_back(1);
-            }
-            for (int i = number_of_extruders / 2 + 1; i < number_of_extruders; ++i) {
-                filament_maps.push_back(2);
-            }
+            std::vector<int>filament_maps = get_filament_maps();
 
             std::vector<unsigned int> nozzle_cur_filament_ids(nozzle_nums, -1);
             unsigned int current_filament_id = m_wipe_tower_data.tool_ordering.first_extruder();
@@ -2806,6 +2799,7 @@ void Print::_make_wipe_tower()
                     wipe_tower.plan_toolchange((float) layer_tools.print_z, (float) layer_tools.wipe_tower_layer_height, current_filament_id, filament_id,
                                                m_config.prime_volume, volume_to_purge);
                     current_filament_id                = filament_id;
+                    nozzle_cur_filament_ids[nozzle_id]   = filament_id;
                 }
                 layer_tools.wiping_extrusions().ensure_perimeters_infills_order(*this);
 
diff --git a/src/libslic3r/Print.hpp b/src/libslic3r/Print.hpp
index 537b1a722f..40405a537d 100644
--- a/src/libslic3r/Print.hpp
+++ b/src/libslic3r/Print.hpp
@@ -936,6 +936,7 @@ public:
 
     void update_filament_maps_to_config(std::vector<int> f_maps);
     std::vector<int> get_filament_maps() const;
+    // get the group label of filament
     size_t get_extruder_id(unsigned int filament_id) const;
 
     bool                        enable_timelapse_print() const;
diff --git a/src/libslic3r/PrintConfig.cpp b/src/libslic3r/PrintConfig.cpp
index 7f64d87128..4065c4e317 100644
--- a/src/libslic3r/PrintConfig.cpp
+++ b/src/libslic3r/PrintConfig.cpp
@@ -56,7 +56,7 @@ namespace Slic3r {
 size_t get_extruder_index(const GCodeConfig& config, unsigned int filament_id)
 {
     if (filament_id < config.filament_map.size()) {
-        return config.filament_map.get_at(filament_id);
+        return config.filament_map.get_at(filament_id)-1;
     }
     return 0;
 }