Adding dual color 3MF export example

examples/dual_color_3mf.py

@@ -0,0 +1,68 @@
+"""
+
+Dual Color Export to 3MF Format
+
+name: dual_color_3mf.py
+by:   Gumyr
+date: August 13th 2023
+
+desc: The 3MF mesh format supports multiple colors which can be used on
+      multi-filament 3D printers. This example creates an tile pattern
+      with an insert and background in different colors.
+
+license:
+
+    Copyright 2023 Gumyr
+
+    Licensed under the Apache License, Version 2.0 (the "License");
+    you may not use this file except in compliance with the License.
+    You may obtain a copy of the License at
+
+        http://www.apache.org/licenses/LICENSE-2.0
+
+    Unless required by applicable law or agreed to in writing, software
+    distributed under the License is distributed on an "AS IS" BASIS,
+    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+    See the License for the specific language governing permissions and
+    limitations under the License.
+
+"""
+from build123d import *
+from ocp_vscode import *
+
+
+# Create a simple tile pattern
+with BuildSketch() as inset_pattern:
+    with BuildLine() as bl:
+        Polyline((9, 9), (1, 5), (-0.5, 0))
+        offset(amount=1, side=Side.LEFT)
+    make_face()
+    split(bisect_by=Plane(origin=(0, 0, 0), z_dir=(-1, 1, 0)))
+    mirror(about=Plane(origin=(0, 0, 0), z_dir=(-1, 1, 0)))
+    mirror(about=Plane.YZ)
+    mirror(about=Plane.XZ)
+
+# Create the background field object for the tile
+with BuildPart() as outset_builder:
+    with BuildSketch():
+        Rectangle(20, 20)
+        add(inset_pattern.sketch, mode=Mode.SUBTRACT)
+    extrude(amount=1)
+
+# Create the inset object for the tile
+with BuildPart() as inset_builder:
+    add(inset_pattern.sketch)
+    extrude(amount=1)
+
+# Assign colors to the tile parts
+outset = outset_builder.part
+outset.color = Color(0.137, 0.306, 0.439)  # Tealish
+inset = inset_builder.part
+inset.color = Color(0.980, 0.973, 0.749)  # Goldish
+
+show(inset, outset)
+
+# Export the tile with the units as CM
+exporter = Mesher(unit=Unit.CM)
+exporter.add_shape([inset, outset])
+exporter.write("dual_color.3mf")