diff --git a/src/libslic3r/Extruder.cpp b/src/libslic3r/Extruder.cpp
index 2abe138b3..f8cba0d0b 100644
--- a/src/libslic3r/Extruder.cpp
+++ b/src/libslic3r/Extruder.cpp
@@ -18,6 +18,11 @@ Extruder::Extruder(unsigned int id, GCodeConfig *config, bool share_extruder) :
     m_e_per_mm3 /= this->filament_crossection();
 }
 
+unsigned int Extruder::extruder_id() const
+{
+    return get_extruder_index(m_id);
+}
+
 double Extruder::extrude(double dE)
 {
     // BBS
diff --git a/src/libslic3r/Extruder.hpp b/src/libslic3r/Extruder.hpp
index 4bf74389f..123bfc87f 100644
--- a/src/libslic3r/Extruder.hpp
+++ b/src/libslic3r/Extruder.hpp
@@ -30,13 +30,7 @@ public:
 
     unsigned int id() const { return m_id; }
 
-    unsigned int extruder_id() const
-    {
-        //TODO: get extruder id
-        unsigned int extruder_id = -1;
-        // get matched id
-        return extruder_id;
-    }
+    unsigned int extruder_id() const;
     double extrude(double dE);
     double retract(double length, double restart_extra);
     double unretract();
diff --git a/src/libslic3r/GCode.cpp b/src/libslic3r/GCode.cpp
index 751248ceb..c0daca1b1 100644
--- a/src/libslic3r/GCode.cpp
+++ b/src/libslic3r/GCode.cpp
@@ -375,7 +375,7 @@ static std::vector<Vec2d> get_path_of_change_filament(const Print& print)
         if (new_filament_id != -1 && new_filament_id != tcr.new_tool)
             throw Slic3r::InvalidArgument("Error: WipeTowerIntegration::append_tcr was asked to do a toolchange it didn't expect.");
 
-        int new_extruder_id = gcodegen.get_extruder_id(new_filament_id);
+        int new_extruder_id = get_extruder_index(new_filament_id);
         std::string gcode;
 
         // Toolchangeresult.gcode assumes the wipe tower corner is at the origin (except for priming lines)
@@ -1865,10 +1865,10 @@ void GCode::_do_export(Print& print, GCodeOutputStream &file, ThumbnailsGenerato
     m_cooling_buffer = make_unique<CoolingBuffer>(*this);
     m_cooling_buffer->set_current_extruder(initial_extruder_id);
 
-    int extruder_id = get_extruder_id(initial_extruder_id);
+    int extruder_id = get_extruder_index(initial_extruder_id);
 
     // Emit machine envelope limits for the Marlin firmware.
-    this->print_machine_envelope(file, print);
+    this->print_machine_envelope(file, print, initial_extruder_id);
 
     // Disable fan.
     if (print.config().close_fan_the_first_x_layers.get_at(initial_extruder_id)) {
@@ -5296,7 +5296,7 @@ std::string GCode::retract(bool toolchange, bool is_last_retraction, LiftType li
 
 std::string GCode::set_extruder(unsigned int filament_id, double print_z, bool by_object)
 {
-    int extruder_id = get_extruder_id(filament_id);
+    int extruder_id = get_extruder_index(filament_id);
     if (!m_writer.need_toolchange(filament_id))
         return "";
 
diff --git a/src/libslic3r/GCode.hpp b/src/libslic3r/GCode.hpp
index f99a63a98..47e63c9db 100644
--- a/src/libslic3r/GCode.hpp
+++ b/src/libslic3r/GCode.hpp
@@ -171,11 +171,6 @@ public:
     // throws std::runtime_exception on error,
     // throws CanceledException through print->throw_if_canceled().
     void            do_export(Print* print, const char* path, GCodeProcessorResult* result = nullptr, ThumbnailsGeneratorCallback thumbnail_cb = nullptr);
-    int             get_extruder_id(unsigned int) {
-        //TODO: get matched extruder
-        int extruder_id = -1;
-        return extruder_id;
-    };
     //BBS: set offset for gcode writer
     void set_gcode_offset(double x, double y) { m_writer.set_xy_offset(x, y); m_processor.set_xy_offset(x, y);}
 
diff --git a/src/libslic3r/PresetBundle.cpp b/src/libslic3r/PresetBundle.cpp
index d914efef4..2d32c5c51 100644
--- a/src/libslic3r/PresetBundle.cpp
+++ b/src/libslic3r/PresetBundle.cpp
@@ -1990,6 +1990,12 @@ DynamicPrintConfig PresetBundle::full_fff_config() const
 
     // BBS
     size_t  num_filaments = this->filament_presets.size();
+
+    // todo multi_extruders: to delete
+    for (size_t i = 0; i < num_filaments; ++i) {
+        this->filament_maps.push_back(1);
+    }
+
     auto* extruder_diameter = dynamic_cast<const ConfigOptionFloats*>(out.option("nozzle_diameter"));
     // Collect the "compatible_printers_condition" and "inherits" values over all presets (print, filaments, printers) into a single vector.
     std::vector<std::string> compatible_printers_condition;
diff --git a/src/libslic3r/PresetBundle.hpp b/src/libslic3r/PresetBundle.hpp
index 5e7f64ecb..0942e45ea 100644
--- a/src/libslic3r/PresetBundle.hpp
+++ b/src/libslic3r/PresetBundle.hpp
@@ -125,7 +125,8 @@ public:
     std::map<int, DynamicPrintConfig> filament_ams_list;
     std::vector<std::vector<std::string>> ams_multi_color_filment;
 
-    std::vector<int>    filament_maps;
+    // todo multi_extruders: delete mutable
+    mutable std::vector<int>    filament_maps;
     // Calibrate
     Preset const * calibrate_printer = nullptr;
     std::set<Preset const *> calibrate_filaments;
diff --git a/src/libslic3r/PrintConfig.cpp b/src/libslic3r/PrintConfig.cpp
index 704222325..d25d2121e 100644
--- a/src/libslic3r/PrintConfig.cpp
+++ b/src/libslic3r/PrintConfig.cpp
@@ -54,6 +54,12 @@ namespace Slic3r {
 #define L(s) (s)
 #define _(s) Slic3r::I18N::translate(s)
 
+size_t get_extruder_index(unsigned int filament_id)
+{
+    // todo multi_extruders:
+    return 0;
+}
+
 static t_config_enum_names enum_names_from_keys_map(const t_config_enum_values &enum_keys_map)
 {
     t_config_enum_names names;
@@ -5378,13 +5384,14 @@ bool DynamicPrintConfig::support_different_extruders(int& extruder_count)
         int size = nozzle_diameters_opt->size();
         extruder_count = size;
         auto extruder_variant_opt = dynamic_cast<const ConfigOptionStrings*>(this->option("extruder_variant_list"));
-        for (int index = 0; index < size; index++)
-        {
-            std::string variant = extruder_variant_opt->get_at(index);
-            std::vector<std::string> variants_list;
-            boost::split(variants_list, variant, boost::is_any_of(","), boost::token_compress_on);
-            if (!variants_list.empty())
-                variant_set.insert(variants_list.begin(), variants_list.end());
+        if (extruder_variant_opt != nullptr) {
+            for (int index = 0; index < size; index++) {
+                std::string variant = extruder_variant_opt->get_at(index);
+                std::vector<std::string> variants_list;
+                boost::split(variants_list, variant, boost::is_any_of(","), boost::token_compress_on);
+                if (!variants_list.empty())
+                    variant_set.insert(variants_list.begin(), variants_list.end());
+            }
         }
     }
 
diff --git a/src/libslic3r/PrintConfig.hpp b/src/libslic3r/PrintConfig.hpp
index cec514242..846112cb2 100644
--- a/src/libslic3r/PrintConfig.hpp
+++ b/src/libslic3r/PrintConfig.hpp
@@ -364,11 +364,7 @@ static std::string get_bed_temp_1st_layer_key(const BedType type)
     return "";
 }
 
-static size_t get_extruder_index(unsigned int filament_id)
-{
-    // todo:
-    return 0;
-}
+size_t get_extruder_index(unsigned int filament_id);
 
 #define CONFIG_OPTION_ENUM_DECLARE_STATIC_MAPS(NAME) \
     template<> const t_config_enum_names& ConfigOptionEnum<NAME>::get_enum_names(); \
diff --git a/src/libslic3r/PrintObject.cpp b/src/libslic3r/PrintObject.cpp
index 86bbc4373..29321795a 100644
--- a/src/libslic3r/PrintObject.cpp
+++ b/src/libslic3r/PrintObject.cpp
@@ -714,6 +714,7 @@ bool PrintObject::invalidate_state_by_config_options(
             steps.emplace_back(posPerimeters);
         } else if (opt_key == "gap_infill_speed" || opt_key == "filter_out_gap_fill") {
             // Return true if gap-fill speed has changed from zero value to non-zero or from non-zero value to zero.
+            // todo multi_extruders: Parameter migration between single and double extruder printers
             auto is_gap_fill_changed_state_due_to_speed = [&opt_key, &old_config, &new_config]() -> bool {
                 if (opt_key == "gap_infill_speed") {
                     const auto *old_gap_fill_speed = old_config.option<ConfigOptionFloat>(opt_key);