diff --git a/src/libslic3r/FilamentGroup.cpp b/src/libslic3r/FilamentGroup.cpp
index 675f64a11..6b932df3d 100644
--- a/src/libslic3r/FilamentGroup.cpp
+++ b/src/libslic3r/FilamentGroup.cpp
@@ -84,12 +84,13 @@ namespace Slic3r
 
 
     // only support extruder nums with 2, try to swap the master extruder id with the other extruder id
-    bool optimize_group_for_master_extruder(const std::vector<unsigned int>& used_filaments,const FilamentGroupContext& ctx, std::vector<int>& filament_map)
+    std::vector<int> optimize_group_for_master_extruder(const std::vector<unsigned int>& used_filaments,const FilamentGroupContext& ctx, std::vector<int>& filament_map)
     {
+        std::vector<int> ret = filament_map;
         std::unordered_map<int, std::set<int>> groups;
         for (size_t idx = 0; idx < used_filaments.size(); ++idx) {
             int filament_id = used_filaments[idx];
-            int group_id = filament_map[filament_id];
+            int group_id = ret[filament_id];
             groups[group_id].insert(filament_id);
         }
 
@@ -99,12 +100,11 @@ namespace Slic3r
         if (can_swap_groups(none_master_extruder_id, groups[none_master_extruder_id], ctx.machine_info.master_extruder_id, groups[ctx.machine_info.master_extruder_id], ctx)
             && groups[none_master_extruder_id].size()>groups[ctx.machine_info.master_extruder_id].size()) {
             for (auto fid : groups[none_master_extruder_id])
-                filament_map[fid] = ctx.machine_info.master_extruder_id;
+                ret[fid] = ctx.machine_info.master_extruder_id;
             for (auto fid : groups[ctx.machine_info.master_extruder_id])
-                filament_map[fid] = none_master_extruder_id;
-            return true;
+                ret[fid] = none_master_extruder_id;
         }
-        return false;
+        return ret;
     }
 
     /**
@@ -124,20 +124,13 @@ namespace Slic3r
     std::vector<int> select_best_group_for_ams(const std::vector<std::vector<int>>& map_lists, const std::vector<unsigned int>& used_filaments, const std::vector<Color>& used_filament_colors_, const std::vector<std::vector<Color>>& ams_filament_colors_,const double color_threshold)
     {
         using namespace FlushPredict;
-        std::vector<Color>used_filament_colors;
+        std::vector<Color>used_filament_colors=used_filament_colors_;
         std::vector<std::vector<Color>>ams_filament_colors(2);
-        for (auto& item : used_filament_colors_)
-            used_filament_colors.emplace_back(item);
+        for (size_t idx = 0; idx < std::min(ams_filament_colors.size(), ams_filament_colors_.size()); ++idx)
+            ams_filament_colors[idx] = ams_filament_colors_[idx];
 
         const double ams_color_dist_threshold = used_filaments.size() * color_threshold;
 
-        for (size_t idx = 0; idx < ams_filament_colors_.size(); ++idx) {
-            std::vector<Color> tmp;
-            for (auto& item : ams_filament_colors_[idx])
-                tmp.emplace_back(item);
-            ams_filament_colors[idx] = std::move(tmp);
-        }
-
         int best_cost = std::numeric_limits<int>::max();
         std::vector<int>best_map;
         for (auto& map : map_lists) {
@@ -169,7 +162,7 @@ namespace Slic3r
                 std::vector<int>l_nodes(group_colors[i].size()), r_nodes(ams_filament_colors[i].size());
                 std::iota(l_nodes.begin(), l_nodes.end(), 0);
                 std::iota(r_nodes.begin(), r_nodes.end(), 0);
-                GeneralMinCostSolver mcmf(distance_matrix, l_nodes, r_nodes);
+                MatchModeGroupSolver mcmf(distance_matrix, l_nodes, r_nodes,std::vector<int>(r_nodes.size(),l_nodes.size()));
                 auto ams_map = mcmf.solve();
 
                 for (size_t idx = 0; idx < ams_map.size(); ++idx) {
@@ -519,11 +512,11 @@ namespace Slic3r
         std::vector<int>machine_filament_capacity(machine_filament_list.size());
         for (size_t idx = 0; idx < machine_filament_capacity.size(); ++idx) {
             if (machine_filament_list[idx].is_extended) {
-                // extend filaments can at most map one filaments
-                machine_filament_capacity[idx] = ctx.group_info.ignore_ext_filament ? 0 : 1;
+                machine_filament_capacity[idx] = 1; // extend filaments can at most map one filaments
             }
-            else
+            else {
                 machine_filament_capacity[idx] = l_nodes.size();  // AMS filaments can map multiple filaments
+            }
         }
 
         std::vector<int>extruder_filament_count(2, 0);
@@ -665,12 +658,13 @@ namespace Slic3r
         auto used_filaments = collect_sorted_used_filaments(ctx.model_info.layer_filaments);
 
         std::vector<int> ret = calc_min_flush_group(cost);
-
-        optimize_group_for_master_extruder(used_filaments, ctx, ret); // ignore the return value
-
         std::vector<std::vector<int>> memoryed_maps = this->m_memoryed_groups;
         memoryed_maps.insert(memoryed_maps.begin(), ret);
 
+        std::vector<int> optimized_ret = optimize_group_for_master_extruder(used_filaments, ctx, ret);
+        if (optimized_ret != ret)
+            memoryed_maps.insert(memoryed_maps.begin(), optimized_ret);
+
         std::vector<Color> used_colors;
         for (const auto& f : used_filaments)
             used_colors.push_back(Color(ctx.model_info.filament_colors[f]));
@@ -678,9 +672,9 @@ namespace Slic3r
         std::vector<std::vector<Color>> ams_colors;
         for (const auto& filament_info : ctx.machine_info.machine_filament_info) {
             ams_colors.emplace_back();
-            for (const auto& info : filament_info)
-                if (!ctx.group_info.ignore_ext_filament || !info.is_extended)
-                    ams_colors.back().push_back(info.color);
+            for (const auto& info : filament_info) {
+                ams_colors.back().push_back(info.color);
+            }
         }
 
         ret = select_best_group_for_ams(memoryed_maps, used_filaments, used_colors, ams_colors);
diff --git a/src/libslic3r/FilamentGroup.hpp b/src/libslic3r/FilamentGroup.hpp
index 8dc61e64c..da72d2b20 100644
--- a/src/libslic3r/FilamentGroup.hpp
+++ b/src/libslic3r/FilamentGroup.hpp
@@ -95,7 +95,7 @@ namespace Slic3r
 
     std::vector<int> select_best_group_for_ams(const std::vector<std::vector<int>>& map_lists, const std::vector<unsigned int>& used_filaments, const std::vector<FilamentGroupUtils::Color>& used_filament_colors_, const std::vector<std::vector<FilamentGroupUtils::Color>>& ams_filament_colros_,const double color_delta_threshold = 20);
 
-    bool optimize_group_for_master_extruder(const std::vector<unsigned int>& used_filaments, const FilamentGroupContext& ctx, std::vector<int>& filament_map);
+    std::vector<int> optimize_group_for_master_extruder(const std::vector<unsigned int>& used_filaments, const FilamentGroupContext& ctx, const std::vector<int>& filament_map);
 
     bool can_swap_groups(const int extruder_id_0, const std::set<int>& group_0, const int extruder_id_1, const std::set<int>& group_1, const FilamentGroupContext& ctx);
 
diff --git a/src/libslic3r/FilamentGroupUtils.cpp b/src/libslic3r/FilamentGroupUtils.cpp
index 3f2bb5c5f..e8077bb18 100644
--- a/src/libslic3r/FilamentGroupUtils.cpp
+++ b/src/libslic3r/FilamentGroupUtils.cpp
@@ -71,7 +71,7 @@ namespace FilamentGroupUtils
     }
 
 
-    std::vector<std::vector<FilamentInfo>> build_machine_filaments(const std::vector<std::vector<DynamicPrintConfig>>& filament_configs)
+    static std::vector<std::vector<FilamentInfo>> build_full_machine_filaments(const std::vector<std::vector<DynamicPrintConfig>>& filament_configs)
     {
         // defualt size set to 2
         std::vector<std::vector<FilamentInfo>> machine_filaments(2);
@@ -79,8 +79,8 @@ namespace FilamentGroupUtils
             auto& arr = filament_configs[idx];
             for (auto& item : arr) {
                 FilamentInfo temp;
-                std::string type = "PLA";
-                std::string color = "#FFFFFF";
+                std::string type;
+                std::string color;
                 std::string tray_name;
 
                 if (auto color_ptr = item.option<ConfigOptionStrings>("filament_colour"); color_ptr)
@@ -90,7 +90,10 @@ namespace FilamentGroupUtils
                 if (auto tray_ptr = item.option<ConfigOptionStrings>("tray_name"); tray_ptr)
                     tray_name = tray_ptr->get_at(0);
 
-                temp.color = color.empty() ? Color() : Color(color);
+                if (color.empty() || type.empty() || tray_name.empty())
+                    continue;
+
+                temp.color = Color(color);
                 temp.type =type;
                 temp.extruder_id = idx;
                 temp.is_extended = tray_name == "Ext"; // hard-coded ext flag
@@ -100,6 +103,36 @@ namespace FilamentGroupUtils
         return machine_filaments;
     }
 
+    std::vector<std::vector<FilamentInfo>> build_machine_filaments(const std::vector<std::vector<DynamicPrintConfig>>& filament_configs, const std::vector<std::map<int, int>>& ams_counts, bool ignore_ext_filament)
+    {
+        std::vector<std::vector<FilamentInfo>> ret(2);
+        std::vector<int> ams_size(2, 0);
+        std::vector<std::vector<FilamentInfo>> full_machine_filaments = build_full_machine_filaments(filament_configs);
+        assert(full_machine_filaments.size() == 2);
+        for (size_t idx = 0; idx < std::min(ams_counts.size(),ams_size.size()); ++idx) {
+            const auto& ams_count = ams_counts[idx];
+            for (auto iter = ams_count.begin(); iter != ams_count.end(); ++iter) {
+                ams_size[idx] += iter->first * iter->second;
+            }
+        }
+
+        assert(full_machine_filaments.size() == ams_size.size());
+        for (size_t idx = 0; idx < std::min(ams_size.size(), full_machine_filaments.size()); ++idx) {
+            std::vector<FilamentInfo> tmp;
+            bool accept_ext_filament = ams_size[idx] == 0 && !ignore_ext_filament;
+
+            for (size_t j = 0; j < full_machine_filaments[idx].size(); ++j) {
+                auto machine_filament = full_machine_filaments[idx][j];
+                if (!full_machine_filaments[idx][j].is_extended)
+                    tmp.emplace_back(machine_filament);
+                else if (accept_ext_filament)
+                    tmp.emplace_back(machine_filament);
+            }
+            ret[idx] = std::move(tmp);
+        }
+        return ret;
+    }
+
     bool collect_unprintable_limits(const std::vector<std::set<int>>& physical_unprintables, const std::vector<std::set<int>>& geometric_unprintables, std::vector<std::set<int>>& unprintable_limits)
     {
         unprintable_limits.clear();
diff --git a/src/libslic3r/FilamentGroupUtils.hpp b/src/libslic3r/FilamentGroupUtils.hpp
index 533613ff2..76430957c 100644
--- a/src/libslic3r/FilamentGroupUtils.hpp
+++ b/src/libslic3r/FilamentGroupUtils.hpp
@@ -62,7 +62,7 @@ namespace Slic3r
 
         std::vector<int> calc_max_group_size(const std::vector<std::map<int, int>>& ams_counts,bool ignore_ext_filament);
 
-        std::vector<std::vector<FilamentInfo>> build_machine_filaments(const std::vector<std::vector<DynamicPrintConfig>>& filament_configs);
+        std::vector<std::vector<FilamentInfo>> build_machine_filaments(const std::vector<std::vector<DynamicPrintConfig>>& filament_configs, const std::vector<std::map<int, int>>& ams_counts, bool ignore_ext_filament);
 
         bool collect_unprintable_limits(const std::vector<std::set<int>>& physical_unprintables, const std::vector<std::set<int>>& geometric_unprintables, std::vector<std::set<int>>& unprintable_limits);
 
diff --git a/src/libslic3r/GCode/ToolOrdering.cpp b/src/libslic3r/GCode/ToolOrdering.cpp
index 7ce9a966d..1948e5e7a 100644
--- a/src/libslic3r/GCode/ToolOrdering.cpp
+++ b/src/libslic3r/GCode/ToolOrdering.cpp
@@ -969,13 +969,15 @@ std::vector<int> ToolOrdering::get_recommended_filament_maps(const std::vector<s
         };
 
     std::vector<int>ret(filament_nums, 0);
+    bool ignore_ext_filament = false; // TODO: read from config
     // if mutli_extruder, calc group,otherwise set to 0
     if (extruder_nums == 2) {
         std::vector<std::string> extruder_ams_count_str = print_config.extruder_ams_count.values;
         auto extruder_ams_counts = get_extruder_ams_count(extruder_ams_count_str);
-        std::vector<int> group_size = calc_max_group_size(extruder_ams_counts, false);
+        std::vector<int> group_size = calc_max_group_size(extruder_ams_counts, ignore_ext_filament);
+
+        auto machine_filament_info = build_machine_filaments(print->get_extruder_filament_info(), extruder_ams_counts, ignore_ext_filament);
 
-        auto machine_filament_info = build_machine_filaments(print->get_extruder_filament_info());
         std::vector<std::string> filament_types = print_config.filament_type.values;
         std::vector<std::string> filament_colours = print_config.filament_colour.values;
 
@@ -985,12 +987,12 @@ std::vector<int> ToolOrdering::get_recommended_filament_maps(const std::vector<s
         FGMode fg_mode = mode == FilamentMapMode::fmmAutoForMatch ? FGMode::MatchMode: FGMode::FlushMode;
 
         std::vector<std::set<int>> ext_unprintable_filaments;
-        collect_unprintable_limits(physical_unprintables, geometric_unprintables, ext_unprintable_filaments);  // TODO: throw exception if fail or set it to status
+        collect_unprintable_limits(physical_unprintables, geometric_unprintables, ext_unprintable_filaments);
 
         FilamentGroupContext context;
         {
             context.model_info.flush_matrix = std::move(nozzle_flush_mtx);
-            context.model_info.unprintable_filaments = ext_unprintable_filaments;  // TODO:
+            context.model_info.unprintable_filaments = ext_unprintable_filaments;
             context.model_info.layer_filaments = layer_filaments;
             context.model_info.filament_colors = filament_colours;
             context.model_info.filament_types = filament_types;
@@ -1003,7 +1005,7 @@ std::vector<int> ToolOrdering::get_recommended_filament_maps(const std::vector<s
             context.group_info.max_gap_threshold = 0.01;
             context.group_info.strategy = FGStrategy::BestCost;
             context.group_info.mode = fg_mode;
-            context.group_info.ignore_ext_filament = false; // TODO:
+            context.group_info.ignore_ext_filament = ignore_ext_filament;
         }