This is an incremental improvement on the Dual Extrusion D20 ( http://www.thingiverse.com/thing:24663 ) by rplumley. I reordered the numbers so it is a proper distribution for a gaming die. (Opposing sides add up to 21, no consecutive numbers, etc.)
This is my first attempt at editing an SCAD file and trying dual extrusion printing so special thanks, and apologies, to rplumley et al and to AKAMEDIASYSTEM ( http://www.thingiverse.com/AKAMEDIASYSTEM ) for showing me the ropes.
This can be used for single or dual extrusion. Ignore the _neg. files if you want the solid color.
This is a derivative work, so it is worth taking a read through the previous objects as I don't repeat their notes.
STLs should be fine as is, and the SCAD files included for further tinkering. You will need the OpenSCAD Bitmap Fonts Module ( http://www.thingiverse.com/thing:2054 ) by tbuser for the SCAD scripts to work.
The number sequence was changed from sequential to a proper distribution by means of a lookup table. (embarrassing, but effective) This also means it is rather simple to modify what is printed on each facet with OpenSCAD. The first table "get_num_digits" has a 0 for single character or 1 for two characters. The other two tables "get_digit1" & "get_digit2" are for the first and second character respectively. "get_digits_old" left in place purely for referencing ordering to display.
Caution, I have not had much success with the second color coming out properly in the Makerbot. If you get it to work, or have a necessary fix, let me know in comments!