With most consumer 3D printers, the only way to set the color of an object is to change the filament you’re using before the printing actually starts. That, or to just paint the item after it has already been printed. Full-color 3D printers are just now reaching consumer-level prices, but even that is static after the print has been completed.
That may change soon thanks to a new 3D-printable ink being developed at MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL). Using that ink in a process they’re calling ColorFab makes it possible to change the color of a 3D-printed object, post-printing, by exposing it to different kinds of light. The ColorFab technique can recolor prints multiple times, so you can change the color on a whim.
The process works because the ink itself is activated when it’s exposed to UV light. In its base state, the pigment remains transparent, but becomes colored when UV light is projected onto it. Similarly, visible light will revert the ink back to being transparent.
Right now, the process takes about 20 minutes to complete. But, the team at MIT thinks they can speed that up by using more powerful projectors and higher concentrations of ink. Aside from 3D printing, they envision the same ink being used in a variety of goods—even clothing.