Greg Petchkovsky’s 3D printing project makes a fun point with the help of a color 3D print:

By combining 3d scanning, 3d digital modelling, and 3d printing, it is possible to create amazing and surprising effects, objects that can seamlessly blend between reality and imagination. In this tutorial, I describe the process of making a full colour 3d printed object that seamlessly fits on to a real sandstone wall, producing the illusion that the wall is built from pieces of lego. But the techniques described have a more general usefulness, almost limitless potential, and are easier and less expensive than you might think!

Staring with a real physical object, in this case a sandstone brick wall, I create an inexpensive but high quality digital 3d scan using a stills camera and the program Agisoft Photoscan. I then model the lego brick shapes over this scan using 3d software, I make this model fit perfectly onto the scanned wall by using boolean subtraction, I add colours clone stamped from the photos, correct the scale, and finally I do a colour 3d print, which fits seamlessly onto the sandstone wall, producing a novel illusion that would be difficult to achieve by other methods.

[via Beyond the Beyond]