So, I was watching a video of an objet printer earlier, and it displayed them using white and black plastics materials, as well as a support material in a single print. That alone, is pretty damn amazing. Not only that, but they were able to combine the white and black on some of the sections of the part to produce a seemless gray color. So white, black, and every shade of gray in between is possible to be printed in one part, in theory. This got me thinking..
If they were able to add one extra material option, and you made the colors RED, BLUE, and GREEN.. could you not use them in the same way a computer monitor uses pixels? To produce full color prints out of plastic by combining the different colors together in the model, and the color wouldn't just be surface deep, so it wouldn't have the draw backs that full color SS has.
It would be understandably more difficult to design a part for this though, you'd need to have different bodies inside the file that were assigned the individual colors, most likely. So the STL format, and other common ones alike would be inept. Or, you could just use the files that store the texture as well, and the shapeways computers could sort out where the different color plastics would go based off of the texture map.
Anywho, I know this is lengthy, but the applications for objet printers seem unlimited!