feat(cad): add tracks for the extrusion

cad/build.py

@@ -87,6 +87,8 @@ def build_drive_shaft_mount():
 
 def build_drive_shaft_bar_adapter():
     ext_size = 20
+    ext_track_width = 6.2
+    ext_track_height = 1.8
 
     height = 60
     thickness = 10
@@ -109,8 +111,11 @@ def build_drive_shaft_bar_adapter():
         Cylinder((ext_size / 2) + thickness, height, align=(Align.CENTER, Align.CENTER, Align.MIN))
 
         # hollow the box
-        with Locations((0, 0, thickness)):
-            Box(ext_size, ext_size, height - thickness, align=(Align.CENTER, Align.CENTER, Align.MIN), mode=Mode.SUBTRACT)
+        with BuildSketch(Plane((0, 0, thickness))):
+            Rectangle(ext_size, ext_size)
+            with PolarLocations(ext_size / 2, 4):
+                Rectangle(ext_track_height, ext_track_width, align=(Align.MAX, Align.CENTER), mode=Mode.SUBTRACT)
+        extrude(amount=height - thickness, mode=Mode.SUBTRACT)
 
         # extrusion screw holes
         with Locations((0, 0, height - ext_screw_hole_offset)):