I'm sure we'll be able to texture the 3-d objects at some point...but since they color dynamically I wonder exactly what we have to work with...?
The simplest way to go would be to give 3-d objects moddable skins. That way, you can edit them 2-dimensionally in a template. In grayscale, you can put symbols, shapes, and such on any side of the blocks, or cut out some of the template to make different-shaped blocks, such as triangles, 3-d stars, wangs, etc.
UPDATE: I pounded out a quick set of flowers. back to work

