It is probably safe to say that most of us started our journeys as makers with LEGO bricks when we were children. But at some point, we move on to more sophisticated fabrication methods, like 3D printing. However, LEGO produces a mind-boggling array of parts that are more versatile than you might think. YouTuber Creative Mindstorms has proven that time and time again, with many impressive builds. And how he’s accomplished something that seems almost impossible: a completely functional 3D printer built entirely from LEGO parts.
This is actually the fourth time Creative Mindstorms has built a LEGO 3D printer. The first attempt was about six years ago and though impressive, it printed poorly. Each subsequent attempt was a big improvement and this newest iteration is capable of printing pretty well—on par with the earliest hobbyist 3D printers from a couple of decades ago.
Every part on this 3D printer is a LEGO product, with one exception: the extruder/hot end. LEGO hasn’t ever made anything that could fill that role, so Creative Mindstorms used a handheld 3D printing pen. But everything else, down to the leadscrews and controller, are parts that were sold by LEGO at some point in time.
Structurally, this design is similar to a “bed-slinger” Prusa i3 3D printer. The bed moves in the Y axis on plastic LEGO screws driven by LEGO motors. The X axis gantry is similar. The Z axis moves through a rack-and-pinion system, instead of leadscrews. All of the axes have limit switches for automatic homing and there is a small motor to actuate a mechanism that pushes the 3D printing pen’s extrude button. At the top, there is a filament spool holder that accepts 1kg rolls of PLA, just like any other 3D printer.
The controller is the most surprising part of the entire project. It is a LEGO Mindstorms EV3 P-Brick, which is actually, essentially, a complete single-board computer with a built-in user interface. In this case, it is running the official MicroPython image available from LEGO. The custom code written by Creative Mindstorms is similar to any other 3D printer’s firmware. It accepts standard g-code (created by Cura slicer software) stored as text files. There is even a file selector, so the user can choose the model to print.
The resulting prints are pretty spectacular. They can’t compete with those from modern 3D printers, of course. But they’re very good and the imperfections are mostly the result of using a 3D printing pen (they’re not great) and the lack of part cooling. It is hard to imagine getting better results than this without “cheating” and using real 3D printer parts, but maybe Creative Mindstorms will make more improvements in a couple of years.