My colleague Sean Ragan recently discovered that rather than pay for Shapeways’ colorized outputs, it was easier, cheaper, and more durable to buy the basic white and colorize it with a marker.
The cheapest and, reportedly, strongest material in which Shapeways models are available is called “White, strong and flexible.” I herein report that this material is easily colored with Sharpie-brand permanent markers. The ink does bleed a bit through the material, so experiment in an inconspicuous area or with a test model before attempting detailed work. Shapeways offers through-tinted colorized versions of their basic white material at increased cost; my experience with these is that the color fades rapidly, even without extremes of light or temperature. I was pleased, then, to discover that I could just order the cheap white stuff and use a Sharpie on it. Sharpies are available in a much wider range of colors, too. Here the technique is demonstrated on the most recent version of my Alphabet Die model; the bottoms of the letters are left white to enhance visibility.