Check out this video. It is a 3D printed ZCorp skateboard that is solid enough to be used as a functional prototype. As you watch this, remember - this is made from plaster!
RapidPro also uses ZCorp printers to create rapid prototypes in plaster composites. They can be printed in full colour, up to a build size of 380 x 250 x 200 mm in a single build or larger when built in pieces. Plaster is the most cost effective prototyping available, so call to see if it may be suitable for your next project.