Introducing the MakerLegoBot, a Lego Mindstorms NXT 3D Printer. Come see it live at LegoWorld October 22nd through October 26th, 2010 in Zwolle, The Netherlands, or build your own with detailed instructions!



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.

The MakerLegoBot


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.

An Example Model


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.

Grab A Brick


It took many nights and many iterations to get the feed system working consistently. 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.

Feed Base


The Feed System is removable for debugging and can hold approximately 35 bricks of each type.

Feed System


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.

Placing a Brick


Immediately after placing the Lego, the bottom of the printer head applies pressure to the brick to insure its proper placement. It is critical that the printer is properly aligned during printing, otherwise Legos will not get placed correctly. I've programmed an alignment mode in the printer that allows fine tuning of brick placement.

Pressing a Brick


The base can rotate, allowing additional degrees of freedom for the non-square bricks. The PC Printer application takes into account rotation when determining the order in which to print the bricks. A motor is located in the center beneath the printing plate for rotation, and another motor is used to lock in the plate once rotated.

Rotating the Base


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.

Moving Up


I've modeled the MakerLegoBot in MLCad, so you can build your own! Check out the model page for all the software and instructions necessary to start building.

MLCad Model

I want to thank Lego for sending me a ton of Bricks to make this model possible! I literally ran out of Legos while trying to build this. The MakerLegoBot is my largest Lego project to date, requiring over 2400 bricks!

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