diff --git a/src/libslic3r/GCode/ToolOrdering.cpp b/src/libslic3r/GCode/ToolOrdering.cpp
index 634093d72..2cc39583b 100644
--- a/src/libslic3r/GCode/ToolOrdering.cpp
+++ b/src/libslic3r/GCode/ToolOrdering.cpp
@@ -146,11 +146,6 @@ ToolOrdering::ToolOrdering(const Print &print, unsigned int first_extruder, bool
     this->fill_wipe_tower_partitions(print.config(), object_bottom_z);
 
     this->collect_extruder_statistics(prime_multi_material);
-
-    // Assign custom G-code actions from Model::custom_gcode_per_print_z to their respecive layers,
-    // ignoring the extruder switches, which were processed above, and ignoring color changes for extruders,
-    // that do not print above their respective print_z.
-    this->assign_custom_gcodes(print);
 }
 
 void ToolOrdering::initialize_layers(std::vector<coordf_t> &zs)
diff --git a/src/libslic3r/Print.hpp b/src/libslic3r/Print.hpp
index 4a4ed3964..5e6a26f9d 100644
--- a/src/libslic3r/Print.hpp
+++ b/src/libslic3r/Print.hpp
@@ -242,11 +242,10 @@ private:
 
 struct WipeTowerData
 {
-	WipeTowerData(ToolOrdering &tool_ordering) : tool_ordering(tool_ordering) { clear(); }
     // Following section will be consumed by the GCodeGenerator.
     // Tool ordering of a non-sequential print has to be known to calculate the wipe tower.
     // Cache it here, so it does not need to be recalculated during the G-code generation.
-    ToolOrdering                                          tool_ordering;
+    ToolOrdering                                         &tool_ordering;
     // Cache of tool changes per print layer.
     std::unique_ptr<std::vector<WipeTower::ToolChangeResult>> priming;
     std::vector<std::vector<WipeTower::ToolChangeResult>> tool_changes;
@@ -267,6 +266,14 @@ struct WipeTowerData
         depth = 0.f;
         brim_width = 0.f;
     }
+
+private:
+	// Only allow the WipeTowerData to be instantiated internally by Print, 
+	// as this WipeTowerData shares reference to Print::m_tool_ordering.
+	friend class Print;
+	WipeTowerData(ToolOrdering &tool_ordering) : tool_ordering(tool_ordering) { clear(); }
+	WipeTowerData(const WipeTowerData & /* rhs */) = delete;
+	WipeTowerData &operator=(const WipeTowerData & /* rhs */) = delete;
 };
 
 struct PrintStatistics