Add template for marking bitting positions with a fine point marker

marker_template.py

@@ -0,0 +1,37 @@
+#!/usr/bin/env python3
+
+import cadquery as cq
+from cadquery import exporters
+
+import key_bittings
+from key_bittings import BittingSpecification
+
+extra_key_thickness = 0.8
+extra_key_width = 0.2
+
+marker_width = 1.25
+
+
+def marker_template(spec: BittingSpecification, thickness=1, fillet=0.4):
+    return (
+        cq.Workplane()
+        .box(spec.TFC + spec.positions * spec.BCC,
+             max(spec.depths.values()) + thickness * 2,
+             spec.key_thickness + thickness)
+
+        .faces(">Z").vertices("<XY").workplane(centerOption="CenterOfMass")
+        .center(spec.TFC, thickness + max(spec.depths.values())/2)
+        .rarray(spec.BCC, 1, spec.positions, 1, center=False)
+        .rect(marker_width, max(spec.depths.values())).cutThruAll()
+
+        .edges("not <Z").fillet(fillet)
+
+        .faces("<X").workplane(centerOption="CenterOfMass")
+        .move(0, -thickness)
+        .rect(max(spec.depths.values()) + extra_key_width,
+              spec.key_thickness + extra_key_thickness).cutThruAll()
+    )
+
+
+result = marker_template(key_bittings.national_disc_tumbler)
+exporters.export(result, "national_disc_tumbler_marker_template.stl")