That Lego printer that printed documents with pens was cool and everything, but a Lego 3D printer made from 2400 bricks that builds a Lego creation of your dreams? Now we're talking.
Battlebricks' MakerLegoBot used three Lego Mindstorms NXT kits, along with nine more NXT motors, plus over 2400 bricks to create the 3D printer. Using even more Lego bricks, the mechanical printer arm assembles the bricks one by one, taking print commands via USB from a PC running a Java application.
While it isn't capable of building Death Stars or anything too complex at the moment (in fact, it can only build designs 12 bricks high), you can take a stab at building your own Lego 3D printer as Battlebricks has generously uploaded the instructions. It'll be a costly venture, but I don't have to tell you how much fun you'll have in doing so. [Battlebricks]