LEGO Elements and 3D Printing

One subject that comes up in conversation quite a lot is the idea of 3D printing LEGO compatible objects. Some imagine this as an affordable alternative to buying genuine LEGO elements, but trust me, I’ve tried, and 3D printed objects are NOT viable alternatives to real LEGO bricks. There are some applications of 3D printed objects that can play nicely with your LEGO collection, and the purpose of this article is to demonstrate some creative ways to enhance your LEGO building experience and/or your 3D printing journey.

3D Printed Objects as LEGO alternatives

Let me start out by putting to rest the concept of using 3D printed objects instead of genuine LEGO bricks. THEY DON’T WORK! First of all, there is the issue of printing the objects. Due to the fact that most “standard bricks” are more or less hollow, to even try to print a decent brick you would need to have print support material, which is near impossible to remove from inside of the final part. Secondly, the time to print even a dozen or so bricks is usually quite long (at least an hour on most consumer printers). At that rate, you could sooner gather a very nice real LEGO collection by visiting a couple of local thrift stores, or even picking up pieces you find on the street, then waiting to print a decent collection. Finally, there is the issue of tolerances. The LEGO Brick and Knob configurations are so precise, that the standard margin of error produced by even high quality printers make any 3D printed objects all but impossible to play with like you would a regular LEGO element.

Creating LEGO compatible specialty parts

Aside from trying to print an actual set of LEGO bricks, there are some real LEGO elements that you either can not find through traditional channels, as well as some things that LEGO simply hasn’t produced, and don’t exist as genuine LEGO elements. In the event that you decide you want to create an object that can be used with LEGO bricks, keep the following in mind.

Size Matters

As mentioned the LEGO systems require fairly tight tolerances to maintain a proper connection. As you create your 3D objects, be very aware of the exact size of your object, especially where you intend to connect it to the real LEGO elements. The LEGO Minifigure hand for example, has an inside diameter of 3.18mm (and is the inspiration for 318Labs’ name). A part that is 3.1mm in diameter will fit very loosely, and probably not stay in place well, whereas an object that is 3.2mm in diameter will stress (or possibly break) the connecting element(s).

Make as few knobs as possible

While it may be tempting to print an object that has as many knobs as the LEGO element you intend to attach it to will support, if your object includes knobs (something you would put real LEGO bricks on top of), include as few of them as possible. To illustrate this point, instead of creating a 4×4 knob object (with 16 knobs) that can support a 4×4 rectangular LEGO brick, print only the corner knobs (same size but with only 4 knobs). This will make it much easier to connect the real LEGO element to your 3D printed object.

Wrap knobs in an “oval”

Similarly, if you plan to print an object that connects to knobs (something you would put on top of real ELGO bricks), print a single oval that wraps multiple knobs, instead of circles, like a real LEGO brick would have.

Expedite 3D Printing with Brickify

One amazing tool that has come to my attention recently is Brickify. This is a tool that allows you to mix 3D printed objects with LEGO bricks to reduce the time required to produce 3D objects. This tool is much better (and faster) at producing 3D objects than most people can do by hand. So if possible, create your object, then load it into their tool to do the hard part of making it work with real LEGO bricks.

Give it a Try with Existing 3D Objects from Thingaverse

If you do decide to try printing your own LEGO compatible objects, I’d suggest that you start with some existing objects from a website like Thingaverse first. This will give you a good idea of how well the objects will work with LEGO bricks, and if it will work for your specific application.

Good luck printing LEGO compatible 3D objects! I hope that this will help you have a less frustrating time that I had when I first set out.