Printing LEGO sets can be a great alternative for pieces that are difficult to find or for creating custom-made ones that do not exist.
In this post, we are going to explain in which cases it is a good idea to print LEGO bricks and, when it is a good idea, how to do so.
During the how-to explanation, we will explain how to find the bricks or how to design them yourself. Afterward, we will explain the most important settings you need to keep in mind when you are about to print your LEGO bricks. Lastly, we will talk about the post-production needed in order to make the custom bricks usable and as similar to the original LEGO ones as possible.
After that, we will talk about the differences you can expect when printing with a FFF 3-D printer (the main focus of this article) and an SLA 3-D printer. Ready? Let’s get started!
When should you print a LEGO brick using your 3-D printer?
Printing LEGO bricks yourself can be a great option for parts that are very difficult or expensive to purchase. It is also a great option if you want to create special pieces that simply don’t exist, such as converters that let you fit other types of toys within your LEGO composition.
But, to recreate easy to buy bricks or full sets, the current technology is not there. You will not save much or any money on it, it will take a very long time to get if you are printing large quantities, and the quality you will get will be much lower.
Let’s have a look at each of the situations and explain a bit more why it is or it is not a good idea.
Printing your LEGO bricks for difficult to find or expensive parts
If you need a specific part of your LEGO set and you try to find it online, you might find out that it is very expensive to purchase or it is simply not available.
For example, if you are trying to recreate the original Millenium Falcon, you will find out that part 4095 (Bar 6.6L with Stop Ring) and part 75535 (Technic, Pin Connector Round 2L without Slot) are required pieces in high numbers but also very expensive.
In this case, then, it would be a great option to check if it is possible to recreate this specific parts with your 3-D printer. Because of the high cost of purchasing them, the investment in time and money to produce them on your own makes total sense.
Printing your LEGO bricks for special pieces
Another situation where printing your LEGO bricks makes sense is for special pieces. By special pieces, we mean pieces that are not available in the market.
If, for example, you are designing your own creations and you come up with a specific shape that is not available, printing it with a 3-D printer is one of the few options available.
A common use of this is when integrating other types of toys within your LEGO. This example is very representative. In this case, the creator has designed a piece that connects Duplo to Brio and has named it “Duplo to Brio converter brick”.
Printing your LEGO for widely available bricks
One situation where printing your own LEGO is not a good idea is for widely available bricks. If, for example, you need a bunch of 2 x 4 bricks, printing them is not a very good idea. They are very cheap to buy online and the quality of the bricks produced by LEGO will be much better than anything you can print at home.
Printing your LEGO for full sets
Another situation you might consider when printing your LEGO is to do it for full sets. This is also not a very good idea. In this video, Youtuber Dr. Jake’s Very British Reviews goes through the calculation of printing the full Millenium Falcon UCS (2nd edition).
The cost of printing the 7513 parts would be around $580 in the material only and it would take more than 200 days printing non-stop to have it printed. Counting in the cost of electricity and the maintenance of the 3-D printer, you can see very easily that it would be better to simply purchase this set, which can be found, new, for less than $700.
And that does not even include the difference in quality between a 3-D printed set and a real set from LEGO, nor does it include all the time you will have to spend sanding down the pieces and making sure they look nice and fit together with the other pieces.
How To Print LEGO Bricks Using Your 3-D Printer
Now that we have a better idea of when it makes sense to print LEGO bricks using your 3-D printer, let’s have a look at how you can go about it.
Finding LEGO bricks or designing your own LEGO bricks
If you want to print LEGO bricks using your 3-D printer, the first step is finding the bricks you want to print or designing your own LEGO bricks. As a starting point, it is much easier to find a LEGO brick than having to design it on your own.
However, if the reason you want to print LEGO bricks is that you are creating your own bricks, then you will need to design them. Let’s look into each option and see how you can reach the point where you can print the LEGO brick.
Finding LEGO bricks
If you are simply looking to print a difficult to find or expensive brick, your first step should be to try to find it online. This way, you will save a lot of time and you make sure that the brick that you are printing works. If you design it yourself, you might make a mistake and not realize it until you print it and try to connect it with other original LEGO bricks.
But, if it is online, chances are that many people have already printed and tested those bricks and any possible mistakes have already been corrected.
So, where can you find your LEGO bricks online? The best resource used to be https://printabrick.org/. However, not too long ago, LEGO started targeting the 3D printing maker community with a series of takedown notices. It looks like Print a Brick was affected and, at the time of this writing, the site was not available. However, I am adding the link just in case the site goes back live.
If this site is not an option, there are other sites where you can still find LEGO parts. The two most well known are Thingiverse and MyMiniFactory. In there, you only need to have a look at the specific part you want to see if it is there.
If you cannot find the piece you want online or you are looking to design your own piece, you can also design your own LEGO bricks.
Designing your own LEGO bricks
This process will take you much longer, but it is the only option in some instances, especially if you want to design your own bricks. For this, you will have a steep learning curve if you have never done something similar.
The first step is familiarizing yourself with the LEGO brick dimensions. If you want to build a piece that is compatible with the LEGO bricks, you need to know what measurements you need to use. For that, this resource is incredible. Don’t be discouraged by the sheer amount of information in there. Just start small and cherry-pick what you need. If you are building only a few pieces, you will not need all the information there.
Once you have studied a bit of this resource, you will need software that lets you design and create the LEGO bricks that you want.
In here, you need to pick a CAD-based program that fits your needs and that can export the file to STL. Examples of this are Fusion 360, OpenSCAD, Tinkercad, or SketchUp (for this last one you will need a plugin to export the file).
If you use Tinkercad, you could use this file as a template for designing your own bricks.
Scanning your LEGO bricks
An alternative that might be suitable for some people is scanning the LEGO bricks. For this, you obviously need a 3-D scanner or a 3-D printer with the scanning function integrated. If you have it, though, this is an easy way to recreate some bricks you already have but of which you need more.
For example, if you need the Bar 6.6L with Stop Ring that we mentioned previously, you could purchase only one of them. You could then scan it and print several copies until you reach the number you actually need.
Printing LEGO bricks
Once you have your file in STL, either by downloading a file, scanning a brick, or creating your own design, it is time to print your LEGO brick.
There are two main points of focus when printing your LEGO bricks. The material you are going to use and the settings you will select. Let’s look at each of them.
Materials to print LEGO bricks
If you are a bit familiar with LEGO, you will know that LEGO bricks are done with ABS plastic, a very durable and stable plastic that cannot be easily recycled. When printing your LEGO bricks with your 3-D printer, you have mostly two options, ABS and PLA.
Print your LEGO bricks with ABS
The first option is printing your LEGO bricks with ABS. This is our personal recommendation because, by using the same material, you will get a much similar feel, look, and weight. Moreover, out of the two options, ABS is the one with better mechanical properties, so it will last longer and don’t break as easily as PLA will.
The downside is environmental. ABS is a type of plastic that is not easily recyclable. As we explain in our post “Recycling LEGO: Possible Or Not?”, ABS, which is short for Acrylonitrile butadiene styrene, is a plastic that falls onto the category #7 plastics, which are not easy to recycle and hardly ever accepted in recycling centers.
The other downside is that ABS is very sensitive to temperature fluctuations. So, if you print with ABS in a non-enclosed 3-D printer, you might have some problems with temperature changes or draughts that could affect the quality of your 3-D printed bricks.
Print your LEGO bricks with PLA
PLA is the most commonly used material for 3-D printing. So, whereas there might be printers that do not support ABS, almost all printers will work with PLA. It is easier to work with, it has a lower melting point and it is less susceptible to temperature changes than ABS is.
Moreover, it is made from renewable resources such as corn starch, tapioca roots, or sugar cane. This makes it a more sustainable option than ABS.
The main downside, as we have already mentioned, is the mechanical properties. PLA is less resistant and more brittle than ABS is, so it will break more easily when under a condition of stress.
If you would like to know a bit more about both of these materials, All3dp has a great resource where it explains the 25 most popular filaments for 3-D printers, with PLA and ABS being the first and the second respectively.
Settings to print LEGO bricks
Once you have decided which material you want to use to print your LEGO, it is time to choose the right slicer settings for it. Most likely you will need to test a few options until you reach the optimal setting for your specific situation.
Different 3-D printers will require different slicer settings and different people will have different expectations, so it would be impossible to list out all the settings you need in order to 3-D print your LEGO. However, to give you a leg(o) up (sorry for the bad joke), we have listed the principles below:
Layer height
The layer height is one of the most common settings for your 3-D printer. Because LEGO builds its bricks to extremely low tolerances, the accuracy of the 3-D printed bricks needs to be high. Otherwise, it will not fit.
For this reason, the layer height should be either 0.1mm or 0.2mm. This way, you make sure that the quality is high enough so that your custom bricks will fit with the original LEGO bricks.
Nozzle & wall thickness
When printing a LEGO brick, and in order to achieve the best results, it is recommended that the wall thickness of your LEGO bricks is an exact multiple of the nozzle diameter of the printer. So, for a standard 1.6mm thick wall, a nozzle of 0.4mm (one of the most common ones) would be perfect. However, if you have a nozzle of 0.5mm that cannot be adjusted, you might want to adjust the thickness of the wall of your LEGO brick to a multiple of 0.5mm for the best results.
If you want to learn a bit more about this, have a look at this and this resource.
Calibration
Another important setting, and a very critical one for that matter, is to have a properly calibrated first layer. If you don’t get your first layer right, no matter what the other settings are, you are bound to have wrong measurements and, as a result, custom bricks that do not fit with the LEGO original ones.
So, before you start printing, make sure your 3-D printer is calibrated. This resource from All3DP is a great starting point to ensure your 3-D printer is properly calibrated before you start printing your bricks.
Post-processing LEGO bricks
So, now that your bricks are printed, it is time to do a bit of post-processing before you can call the job done. This will depend on the type of brick you have printed, on the 3-D printer you have used and on your expectations, but we have listed the three main steps you can potentially encounter when post-processing your LEGO bricks.
Removing the supports of your LEGO bricks
Depending on which type of brick you are printing or which type of 3-D printer you are using, you might need to print some supports in order to get the brick right. Also, if you printed your LEGO bricks with a brim, you would need to take that out as well.
This should be standard procedure for anything you print in your 3-D printer, so I will not extend too much with it. Just a tip though. If you are printing with ABS, give the bricks an acetone bath to smooth them with the acetone vapors. Just remember not to leave it too long, otherwise, you will damage the brick and it will not fit anymore.
Sanding your LEGO bricks
Once you have taken out the support, it might be a good idea to sand your LEGO bricks. This will smooth it out even further, removing any small pieces that have stayed and that should not be there.
This is also a good moment to sand the exterior faces to clean off any burrs. The more accurate and methodical you are with this process, the better your custom LEGO pieces will look.
Painting your LEGO bricks
The last step, if you want to make your custom LEGO pieces as similar to the original ones as possible is to paint them. If you don’t, chances are the color will be off and the glossy finish of the original LEGO pieces will not be there either.
If you are going to paint it, though, be careful with the amount of paint you use. Because of the very tight tolerances, if you put a layer of paint that is too thick, that might cause the brick no longer fitting with the original ones.
The best recommendation we have found online for this is to use spray paint and to use is as lightly as possible. So, you would first spray a super light coat and wait until it dries. If, after it is dry, you see that another session is needed, then go back and spray again. But, if you spray on it heavily, you risk adding too much paint and making the pieces no longer compatible.
Which type of 3-D Printer works best for printing LEGO bricks?
So far we have talked mostly about FFF 3-D printers because they are the most common. However, before finishing, it is worth mentioning the differences in LEGO bricks between the two most common types of 3-D printers, FFF 3-D printers, and SLA 3D printing. Although they share the majority of the characteristics that we have explained before, there are certain differences that are worth highlighting.
Printing LEGO bricks with a FFF 3-D printer
The FFF (Fused filament fabrication ) 3-D printers, also known under the trademarked term fused deposition modeling (FDM), are, as just mentioned, the most common type of 3-D printers available. This type of printer is a 3D printing process that uses a continuous filament of a thermoplastic material, such as PLA or ABS.
The main advantage of this type of 3-D printer compared to an SLA 3-D printer is cost. The price per object is lower. Moreover, it is much more convenient and easy to use and the materials are safer and do not require careful handling.
The main disadvantage is the accuracy. Due to the nature of the machine and the current technology, this type of 3-D printer is much less accurate than the SLA 3-D printer. This can become a problem for LEGO bricks because of the extremely low tolerances they are built to.
Printing LEGO bricks with an SLA 3-D printer
The second type of 3-D printer is the SLA 3-D printer. SLA 3-D printer or Stereolithography is a form of 3D printing technology that uses photochemical processes to harden liquid resin into the desired shape.
The main advantage of this type of 3-D printer is that it is extremely accurate. With this type of printing, you will nail the size every time and you will have fewer problems with bricks that are not fitting.
The main disadvantage is the ease of use. Not only do you need to be more careful when printing because of the hazardous materials, but the post-processing usually takes much longer than with a FFF 3-D printer.
In addition to that, printing with this type of 3-D printer is more expensive than with a filament one. But, if you are looking for extremely accurate pieces to always get the right fit, it might be the way to go for you.
Final words
And with this, we have arrived at the end of this post. We hope you were able to understand how you can print LEGO bricks using your 3-D printer.
If you are a maker that likes tinkering with his or her own design, be sure to check our post “How To Make Your Own Building Block Toys” for more ideas on creating your custom building block toys.
Learn More
If you are interested, here is a link to the entire Lego section found on Amazon.