3D printing is incredibly useful but it does have its limitations, one of which is that it's very hard to print anything more visually sophisticated than a single-colored object. Not if you use the process of "computational thermoforming" as developed by the folks at Disney Research.
The process is simple. First, you use a 3D printer to make a negative mold and then fill it with gypsum powder to make your object. Then, using a vacuum former, you shrink a layer of plastic coating over the top of the object to add a layer of detail. The real trick is the computer simulation that performs this process over and over in cyberspace to design an image that is deformed in just the right way that it will look normal when it stretches out over the object.