Last year, Popular Photography had a short but interesting article out about the making of the movie Coraline. In The Technology Behind Coraline, they wrote:
Objet is a company that specializes in rapid prototyping. They produce machines that use inkjet print-heads to spray layer after layer of a UV curable liquid that hardens into a solid. Using a software developed by Laica (not to be confused with camera-maker, Leica), animators were able to create scenes in 3D animation software like Maya and send the results directly to the printer.
Unfortunately, the cheapest printer at Objet will set you back $40,000. Probably out of the range of most props shops. And by “most”, I mean “all”.
That doesn’t mean you can’t use this new technology. Bucknell University, where I got my BA, had these kinds of machines for their Small Business Development Center. If you work at a university theatre, or are still in school yourself, you may find another department has one of these. You may even be able to gain access if you develop a good relationship with that department.