As LEGO prices rise and 3D printing technology continues to improve, it’s natural to ask “can we just print our own LEGO pieces”? Having recently purchased a 3D printer I decided to explore whether this technology puts LEGO’s rich history in premium plastic toys at risk. Let’s learn more about LEGO, plastics, and the future of 3D printing.

A rich history of Moulded ABS Bricks

While many LEGO enthusiasts know that the company began making wooden toys, the key innovation in The LEGO Group’s history was the switch to injection-moulded plastic toys and their focus on interlocking bricks. Let’s start by learning a bit more about this history, the plastics involved, and how the mainstreaming of this technology has created competition in this space.

History of LEGO and plastics

LEGO bricks are made of a type of plastic called acrylonitrile butadiene styrene (ABS). ABS is a strong and durable thermoplastic that is resistant to impact, heat, and chemicals. It is also lightweight and can be easily molded into different shapes, which makes it an ideal material for use in toys like LEGO bricks. Most importantly ABS plastic is also non-toxic and safe for use in children’s toys, which is an important consideration for LEGO as a company that produces toys for children. Additionally, LEGO has strict quality control standards to ensure that its bricks are consistently manufactured to high standards and meet all relevant safety regulations.

Acrylonitrile butadiene styrene comes in small colored granules that get molded into LEGO bricks. (Photo: Wikimedia CC0-1.0)

In recent years, LEGO has also made a commitment to using more sustainable materials in its products through bio-based polyethylene, which is made from sustainably sourced sugarcane, and recycled plastic, which is made from post-consumer plastic waste. In 2018, LEGO announced that it would be investing $400 million to develop new sustainable materials and packaging by 2030. The company has since introduced a number of new products made from sustainable materials, such as plant-based plastic and recycled plastic.

Here’s how The LEGO Group is trying to turn plastic bottles into LEGO bricks. (Photo: The LEGO Group)

LEGO has made changes to the plastic it uses over time. While the basic composition of the plastic remains acrylonitrile butadiene styrene (ABS), the specific formulations and production methods have been refined and improved over the years. For example, in the 1960s and 1970s, LEGO began using a higher-quality ABS plastic that was more durable and resistant to discoloration over time. In the 1980s, LEGO started using a new formulation of ABS plastic that was more flexible and allowed for the creation of thinner and more intricate pieces.

Despite these changes, LEGO has maintained a consistent standard for the quality and durability of its plastic, ensuring that all bricks made from any formulation or material can still interlock with each other and be used to create endless building possibilities.

LEGO Patent

The original patent for the LEGO brick was filed on January 28, 1958, and granted on January 28, 1958. The patent was filed by Ole Kirk Christiansen, the founder of the LEGO Group, and describes the basic design of the LEGO brick, which includes a hollow rectangular shape with four evenly spaced studs on top. The patent also describes the interlocking mechanism of the LEGO brick, which allows the bricks to be stacked and connected securely to create a wide range of different structures. This interlocking mechanism is based on the clutch power of the studs, which allows them to grip each other tightly and hold the bricks together.

One interesting aspect of the LEGO patent is that it does not specifically mention the word “LEGO”. Instead, the patent refers to the toy as a “toy building brick”, which allowed the LEGO Group to trademark the LEGO name separately.

1968 British Patent Application for the LEGO brick depicted on a LEGO VIP print. (Photo: The LEGO Group)

The LEGO patent has been renewed several times since it was first filed in 1958, and LEGO continues to hold multiple patents related to its various building sets and toys. In addition to its patents, LEGO also relies on its trademarks, copyrights, and other intellectual property rights to protect its brand and products from imitation or infringement. The LEGO patent has been the subject of many legal disputes over the years, as other companies have attempted to copy the design of the LEGO brick. However, LEGO has been successful in defending its patent in most cases, and the LEGO brick remains one of the most popular and recognizable toys in the world.

Why ABS?

There are a large amount of different plastics available, each of which are used for different purposes. Of those available you may wonder why LEGO went with Acrylonitrile Butadiene Styrene (ABS). Lets look a little into some common plastics, their strengths and weaknesses and common usage.

• Polypropylene (PP) – PP is a thermoplastic material that is used for a wide range of applications, including packaging, automotive parts, and medical devices. It is durable, heat-resistant, and has a high melting point. Unfortunately PP is susceptible to UV damage causing it to brittle when exposed to sunlight, is highly flammable and ignites easily and softens at temperatures below 0°C.
• Polyvinyl Chloride (PVC) – PVC is a thermoplastic material that is commonly used for pipes, cables, and building materials. It is strong, durable, and resistant to chemicals and weathering, all while being very low cost. Unfortunately PVC products can release harmful chemicals that and are known to release volatile organic compounds contributing to indoor polution, have limited temperature resistence giving it a low maximum operating temperature and has limited durability when exposed to cold temperatures making it brittle and crack over time.
• Acrylonitrile Butadiene Styrene (ABS) – ABS is a thermoplastic material that is used for a wide range of applications, including toys, automotive parts, and electronics. It is strong, durable, has a high impact resistance, has good surface finish allowing it to easily be painted and is easily to process making it a popular choice for manufacturing products. Unfortunately it has poor resistance to UV lights and becomes discolored when exposed to sunlight, has chemical sensitivity causing it to crack and deform and releases unpleasant odors and fumes when melted requireing adequate ventilation.
• Polyethylene Terephthalate (PET) – PET is a thermoplastic material that is commonly used for packaging, such as bottles and containers. It is lightweight, strong, and resistant to moisture and chemicals. Unfortunately it has a low melting point causing it to deform when exposed to heat and has great environmental concerns as it releases greenhouse gases during production and is difficult to recycle.
• Polylactic Acid (PLA) – PLA is a type of biodegradable plastic that is made from renewable resources such as corn starch, sugarcane, or cassava. It is a popular material in 3D printing. It is low cost, rigid and has a low melting point allowing for an ease of use. Unfortunately it has brittleness issues making it prone to crack under certain conditions and has limited chemical sensitivity causing it to react negatively to certain compounds.

As we can see from just these plastics alone there are a lot of benefits and costs of each. Interestingly we have seen the cons of ABS in effect with the yellowing of white pieces when in direct sunlight and the infamous brittle brown that was caused by a chemical reaction between the plastic and the pigment used for coloring.

When it comes to LEGO, ABS is the ideal plastic for most LEGO elements because it is inexpensive, strong, and durable. Injection moulding is a mature technology that produces high-quality parts with incredibly precise tolerances, so long as the mould is high quality and operated corretly – something that The LEGO Group is a leader in globally. Speaking of which, the moulds are expensive, upwards of $200k per mould. Most of all, Injection moulding is fast, the best moulds can produce a batch of parts in about 10 seconds. You can learn more about this process directly from LEGO here.

From Moulding to 3d Printing

I re-raise the existential question here – will 3D printing replace injection moulding? As we explore more about LEGO’s relationship with 3D printing we will see whether or not this new technology poses a threat to the LEGO group.

3D printing, also known as additive manufacturing, is a process of creating physical objects from digital 3D models. This process involves adding material layer by layer until the final object is produced. 3D printing allows for the creation of complex geometries and customized designs that would be difficult or impossible to produce with traditional manufacturing methods. As part of the 3D printing process printer reads the digital file and prints the object layer by layer, adding material until the final object is produced. There are several 3D printing technologies available, including Fused Deposition Modeling (FDM), Stereolithography (SLA), and Selective Laser Sintering (SLS), among others.

1×2 LEGO plate piece modelled in open-source 3D graphics Blender.

3D printing has a wide range of applications, including rapid prototyping, product development, and even the creation of finished products. It has revolutionized the manufacturing industry by allowing for faster and more cost-effective production of parts and components, and has also opened up new opportunities for customization and innovation in product design. As explorerd through interviews with LEGO designers this process has greatly enhanced the LEGO design pipeline allowing for quicker prototyping.

LEGO Digital Designer (LDD) and Bricklink’s Studio 2.0 are software programs that allow consumers to design virtual LEGO models. Users can export these designs and print them using a 3D printer. It is important to note that the resulting printed pieces are not official LEGO pieces and may have compatibility issues with official LEGO products. These tools are also a great way to design LEGO MOCs and leverage the built in Bricklink integration to buy pieces. I personally have lost a lot more time than I would like to admit building designs and submitting them to LEGO IDEAS contests or building MOCs for my personal collection using this tool.

Studio by bricklink allows users to build models before buying pieces.

LEGO’s history with 3D Printing

While LEGO has experimented with 3D printing in the past, it does not currently use 3D printing to produce LEGO pieces for its official product line. The vast majority of LEGO pieces are still manufactured using injection molding, which involves melting plastic pellets and injecting the molten plastic into a mold to create the desired shape. LEGO has used 3D printing in its research and development process to create prototypes and test new designs. This allows the company to quickly create and test new pieces without having to invest in expensive tooling and production equipment.

In 2019 however LEGO released their first tand-alone 3D-printed element, a duck. This 3D-printed element had been included in a special edition set given to participants in the 2019 LEGO Inside Tour and can currently not be purchased directly, however opens the doors for future 3D printed pieces. At the time of writing this article 3 3D printed pieces have been produced in limited quantities; these being the duck, a pogo stick and a drafting arm. I am sure we will see more being produced in the future.

Drafting Arm (part 66237) and Pull-along Duck (part 92898) were the first two officially released 3D Printed LEGO Elements.

Currently in LEGO’s manufacturing 3D printing sits alongside injection moulding technology in the company’s factories. Injection moulding allows the company to make bricks at high speed and at a high quality. Meanwhile newer technology offers support in product innovation and allows LEGO to make a greater variety of elements in smaller volumes.

ABS LEGO pieces vs PLA LEGO pieces

Legality and copyright infringement aside, the big question everyone has is can we print LEGO parts? The answer to this is a restounding YES* however as we dig a little deeper we will start to see why the inclusion of the asterisk in the response is important. For purposes of the comparisons we will be using the printer that I own, Neptune Elegoo 3 Pro printing SUNLU PLA. As 3D printing technology is rapidly evolving and prices dropping it is important to specify what was used. The printer itself is an entry level printer that will set you back $250 USD. As we explored earlier, different plastics have different strengths. Despite my printer printing PLA, the top of the line 3D printers can print plastics such as Acrylonitrile Butadiene Styrene (ABS) as well to give similar qualities to official LEGO bricks. Albeit a very different material some printers can also print resin.

The ELEGOO Neptune 3 Pro is a great entry level printer for those wanting to explore 3D printing. (Photo: Elegoo)

We will compare 2×4 LEGO bricks by comparing original ABS LEGO pieces to a 3D printed PLA LEGO piece. If you purchase such a brick directly from LEGO Pick a Brick without shipping, it will cost you 21 cents. On the other hand, if you print it using my printer at a 20% infill, it will use up 3 grams of material and take a 28-minute print job, costing only 5.3 cents when factoring only the price of material at $17.99 per kg. This is a staggering quarter of the cost. However, you will quickly find that the cost is significantly higher once you factor in the time spent priming, post-processing, and preparing, as you cannot compete with LEGO’s economies of scale and mass production.

Cost aside when you compare the two pieces the biggest differences is accuracy. LEGO bricks made with ABS have a smoof surface with a precision of 10 micrometers or better thanks to injection molding technology, a standard even the best 3d printers will have trouble reaching. Due to the inaccuracy, even when on the best settings the 3D printed parts fail to reach the clutch power of LEGO bricks, with some pieces being unable to fit on original parts all together. Even on the most calibrated 3D printer even a slight variance can lead to inferior parts. The rigidity and weight of the pieces is also notable with the official LEGO brick being lighter with an official weight 2.32 grams vs the printed piece’s 2.97 grams (note, the weight of the printed piece can vary by the settings used during the print). From the top, aside from the LEGO logo the pieces look rather similar. The most notable difference is the markings left behind by the two techniques used to create the pieces with the 3D printed piece showing notable lines of the layers of plastic deposited giving it a rough finish while the ABS brick is smooth bar the injection molding blemish.

To get real and printed bricks to stick you need to play around with the model and your printer settings to get an ideal fit.

When you look at the underside of the bricks printed you start to see issues. Due to the lack of precision of 3D prints, the outter walls of the print are a lot thicker (with a variance of depth) when compared to the LEGO brick. This is mostly done as PLA is less rigid than ABS so to make the brick sturdier more plastic is used. This is evident with how little empty space there is within the brick. The tubes that run through the official brick are a lot deeper than printed bricks affecting the clutch power. Interestingly due to these differences an official LEGO brick was able to stack on top of my printed brick but the inverse could not as the walls were to thick and the tubes were not perfectly aligned to fit on the official brick.

From the bottom the differences between the bricks are noticeable with clutch power being a big differentiator.

In general, LEGO standards exceed those of 3D printing, but 3D printing has valuable applications for creating special or customized parts to supplement your LEGO collection. You can print parts that LEGO does not offer to improve your collection. However, 3D printing cannot replace the parts in your LEGO collection because it does not have the mass production capabilities or injection molding accuracy of LEGO. Additionally, it is important to note that SLA resins used in 3D printing may be toxic when ingested, which may not be suitable for small children. Nonetheless, you should not be discouraged by these downsides and should try to print and build something amazing for yourself because many custom pieces or designs can enhance your LEGO experience.

How can 3D printing enhance the LEGO experience

While 3D printing will not replace your LEGO bricks it can still supplement your LEGO building experience. When I first got my 3D printer, I decided to blend two of my hobbies together enhance my LEGO experience. This involved browsing the internet for things that others had created using their 3D printers. Two great sources for this were thingiverse and printables. In this section, I would like to highlight some models that I have printed and that I believe deserve recognition. Each of the creators has granted permission for their work to be highlighted, and links to the files needed for printing have been provided.

LEGO Compatible Bricks all sizes up to 50×50

FLWE created a large selection of LEGO compatible bricks, all x*y sizes can be configured to fit your needs. These bricks were referenced in the analysis did above when comparing official and LEGO compatible bricks. Despite these bricks not matching the official LEGO brick’s quality it can be a fun supplement to your collection or can be used for low cost prototyping for builds.

Printables creator FLWE created a seriess of LEGO compatible bricks of all sizes up to 50×50 (Photo: FLWE)

LEGO Minifig Hexagons – Extended Edition

To enhance your LEGO minifigure display collection Casadebricks built a beautiful LEGO minifig Hexagons display stand. These display stands can be printed in a variety of configurations to display your figures. These stands can be rested on a surface or nailed into the wall as a hanging display. I personally have been using these stands for each of my collectible minifigure sets as it has a space to insert the 3×4 plate allowing for figures to be cleanly displayed.

The hexagonal minifigure displays by Casadebricks can be configured into any pattern to display your figures.

Modular Display Stands

Of all the prints I have done the stands created by stawiamklocki.pl are by far my favorite. The modular display stands were created with Star Wars in mind but can be customized to a variety of shapes and angles to fit all your display needs. With over 200 files to print from, everything from the base to the arms and heads can be customized to angle your displays and have space for your figures and vehicles to be displayed. This greatly enhances the displayability of the set but also lets you utilize vertical space as multiple sets can be displayed next to each other at overlapping heights.

Stawiamklocki.pl created some amazing customizable vehicle displays that elevate your models to the next level.

LEGO Ruler

@NiraCreationz created a LEGO ruler based on the original designed by LEGO in 2009. This ruler Allows you to measure brick length and heights to improve your LEGO designing experience. Both system and technic bricks can be measured using this stand allowing you to take advantage of angles and shapes in your build quickly without needing to do the calculations.

The LEGO ruler by printables user NIRACreationz is a great way to measure out your pieces and creations. (Photo: NIRACreationz)

LEGO Accessories

Upon comparing my 3D-printed components to those made by LEGO, it’s clear that bars are the most suitable pieces for 3D printing, owing to the clips’ tolerance and the bricks’ clutch power. LEGO hasn’t actually created any 3D-printed parts with studs yet as bars are a lot more forgiving. This is consistent with the observation that accessories remain the most commonly printed pieces in the community. The internet has a plethora of models for your to print and paint to supplement your LEGO minifigures.

Obi-Wan showcasing some examples of accessories you can print to enhance your build. Darth Malgus Lightsaber by Firelord91021, gas mask by garvey64 and brick bounty hunter carbonites by Dingus100.

Conclusion

As we have come to realize, while 3D printing is nifty and can technically print bricks it is important to emphasize that it is a slow, costly alternative to injection moulding. As it stands injection moulding will still remain king for years to come but we should expect the LEGO group to continue using it in the prototyping process (which they have been doing for a long time) and to create unique specialty parts that can not be produced using traditional methods. That being said, a 3D printer is a great way to supplement your hobby and build things that can enhance your LEGO experience.