Watercolor Palette Cups for Mint Tins

Update 2016-04-10: Added a double wide, double high sponge cup and new default arrangement for the OpenSCAD file.

This OpenSCAD program will generate some small cups that can be used to hold watercolor paints. I got the idea from this instructable:
http://www.instructables.com/id/Movable-Pallet-Altoid-Tin-Watercolor-Set/

The author shows "1/2-pans" for watercolors mounted in an Altoid Tin with magnets. Honestly, the commercial ones are probably much cheaper and easier to clean than these