Will Gorman of BattleBricks has built himself the MakerLegoBot, constructed of Lego bricks it constructs with Lego bricks.....

The MakerLegoBot uses 3 Lego Mindstorms NXT Bricks, along with 9 NXT motors, and is inspired by the  by the MakerBot and RepRap teams. A Java Application that runs on the PC takes an .ldr MLCad file, determines a set of print instructions, and then sends the instructions via USB over to the MakerLegoBot for printing. The current design works with 1x2, 2x2, 3x2, 4x2, and 8x2 Lego bricks. Once a brick is grabbed, the next brick in line falls into place. Once a brick is retrieved, the printer head rotates vertically and moves to the exact location where the brick should be placed. The printer then places the brick, and uses an axle based release mechanism to leave the Lego in place. Immediately after placing the Lego, the bottom of the printer head applies pressure to the brick to ensure its proper placement. Once each layer has completed printing, the printer rotates up a single brick height. It can print objects that are up to 12 bricks tall.

the MakerLegoBot, a Lego Mindstorms NXT 3D Printer will be appearing at LegoWorld October 22nd through October 26th, 2010 in Zwolle, The Netherlands. Of course if you cannot wait till then you can always follow the 447 step by step (brick by brick) instructions to make your own...

Thanks to Hack a Day