Will Gorman’s clever “printer” assembles simple models by pulling bricks from a gravity-fed magazine that holds 35 each of five different types of Lego elements.

I’ve always wondered if I could build a Lego machine that assembles Legos. I finally came up with an idea this summer to make it happen. The printer uses 3 Lego Mindstorms NXT Bricks, along with 9 NXT motors, and is inspired by the great work done 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 core concept that makes 3D print of Legos possible is the sticky grab and axle release mechanism. The printer head selects from an array of Lego bricks, moves to the correct location, and then places each Lego in its determined spot.

It took many nights and many iterations to get the feed system working consistently. The current design works with 1×2, 2×2, 3×2, 4×2, and 8×2 Lego bricks. Once a brick is grabbed, the next brick in line falls into place.

Building instructions and software here.