While it's pretty common for people to build their own hot plastic extrusion printers, DLP is a whole 'nother thing. (And it doesn't use lasers - that's SLA). DLP printers use a digital projector shining through the bottom of a clear tank to catalyze a whole layer at a time against a build platform, which then raises up a tiny bit and the process repeats. Unlike the more common type of printers, the software that runs them isn't widely available. You might look at the B9 Creator, which is a DLP printer that's popular among jewelers. The firmware runs on an Arduino, and the software started out as an open-source project, although I'm not sure how open it is at this point.

Andrew Werby
www.computersculpture.com