Lazy update b/c I've barely worked on the OpenSCAD design lately. Have some 3d printing instead.

This is best way I've found to color the recessed text: thinned paint in a syringe. Here are my components:

• 1ml Oral Syringe, Luer Slip Tip
• Dental Pre Bent Needle Tips, 25 Ga
• nail polish or acrylic paint
• thinner for your paint: mineral spirits, acetone

Beautiful!

Nail polish is hideously expensive compared to paint. Next time I'll use high-pigment acrylic paint. Also acrylics can be thinned with water rather than smelly solvents. This nail lacquer was noxious.

Crayon was a half success. It gets caught easily in the extrusion lines. "Ironing" in the 3d printer slicer was mediocre and made the rest of the print look bad.