Non-production items

A non-production LEGO item is an item that has been made without the intention of going into mass-production to get released as an official LEGO product. In most cases, they are not even intended to be seen by the public, and never intended to be acquired by the public. There are many kinds of non-production items, and each usually fills a specific purpose in the LEGO ecosystem.

Prototypes

A prototype is a pre-production item intended to test critical aspects of a product before it is being put into mass production to be released as a product. LEGO prototypes can refer to physical toys like sets and parts, physical media like books and CDs, and digital media like video games.

History

It is unknown when the LEGO Group started using prototyping processes for their products. It is difficult to find information about prototypes from the early years of the company, and it is unclear if prototypes were used at all before the company started producing LEGO bricks in 1949. Information on the earliest LEGO prototype items can most notably be found on the LEGO Group's history website. As a general rule, all LEGO prototypes are produced in-house at the LEGO Group's development headquarters in Billund, with very little being outsourced to other companies. There were also a few other LEGO Futura offices set up around the world which worked with LEGO product concepts and prototypes, but it is not clear what prototypes these offices produced.

Process

The LEGO Group's prototyping process has varied a lot over the company's history, and changed with regard to the available technology and the skills of the employees. Each product category generally required very different approaches.

Because all products are prototyped well in advance before release, it is difficult to pinpoint exactly when a LEGO prototype was made without confirmation from a LEGO employee. For example, while the Homemaker figures released in 1974 and the "stage extra" figure released in 1975, they both might have been prototyped at the same time, but released in different years depending on how long each of them were in development.

LEGO Elements

As most LEGO products are made out of LEGO elements, prototyping elements are an essential part of LEGO development. In general, each LEGO element put into production has a prototype produced for it, that goes through several iterations and stages of testing until it is finalised.

Pre-System (1949-1955)

It is not known how LEGO elements were prototyped in the earliest days of the LEGO brick, but most likely the mould was just iterated on over time, and sent into production when it appeared good enough. Early LEGO elements were not produced by a scientific process, as at this point, the LEGO brick was just another toy in the larger LEGO portfolio.

Early LEGO System (1955-1958)

Little is known of the early days of the LEGO System, but after the LEGO Group shifted focus to developing the LEGO system, more care had to be put into designing the LEGO elements, and as such, prototyping became more important. One very notable prototype is the 2x4 LEGO brick in 1958, which was first prototyped with 2 internal tubes, but later quickly adding a third tube in the middle of the underside of the brick. Several prototype variants of the LEGO brick were also made, in a single mould containing all the concepts for the new LEGO brick. The mould used to prototype the LEGO brick was made out of solid steel, much like a production mould, and is on display in the LEGO Idea House.

LEGO Futura's early days (1959-1969)

As the LEGO system is rapidly expanding, a department for product development is set up: LEGO Futura. They move into the newly built System House, a 2-story building right next to the wooden workshop and Ole Kirk's House. This made prototyping LEGO elements a more organized effort. Prototypes at the time were primarily made out of wood, a skill that the employees already had from the wooden toy production, which shut down in 1959. Many of these wooden prototypes can be seen in the LEGO House in Billund, Denmark. As the LEGO elements around this time started being more detailed, the prototypes were commonly produced in larger scale, often 3 or 6 times larger, in order to sculpt the details more accurately.

LEGO Futura mould prototyping (1969-2001)

In 1969, LEGO Futura opens for LEGO designers being able to request prototype LEGO elements to be produced. These elements went through several stages of prototype production, and prototypes from this era are the most common to find in public.

Handmade prototypes

The first step, and the most simple one, is usually to make handmade approximations of the elements to quickly get the correct shape and general feel of a LEGO element. It was very common to simply cut or glue existing LEGO elements together to create new prototyped LEGO elements. Depending on the skill set of the employee, prototypes could also be hand sculpted using clay, or cast in materials like lead. This process eliminated the need to spend time on creating moulds. Handmade prototypes are rarely found in the wild, as they were commonly discarded once proper prototype moulds were created, and are almost never shown in official LEGO media. One example that demonstrates this part of the prototyping process well is the development of the LEGO minifigure.

Scaled-up prototypes

In order to create highly detailed elements by hand, one method used was to create them in a larger scale first, which could then be scaled down using a pantograph. These pieces are rarely seen, but is known to have been used in even the pre-1970 era, and some prototypes of this kind are visible in the LEGO Minifigure prototype display in the LEGO House's History Collection, and some LEGO Fabuland prototype elements were shown off in the LEGO House's Fabuland exhibit in 2025. No verified examples are known to exist outside the LEGO Group's archives.

Moulded prototypes

Once the important dimensions and details of an element are decided, the next step would be to make properly moulded plastic prototypes. These were produced by making small moulds out of brass, where elements were produced one by one. The elements were designed to fulfil the specific play feature, and rarely focused on durability or any difficulties with mass production. The elements were designed to only be put together a few times and did not have to adhere to the normal quality standards of other LEGO elements sold to the public, and the prototype moulds were in general very rough and not polished, sometimes even with clear defects or mistakes. Elements could go through several stages of iteration, usually in order to improve the element or increase compatibility with the rest of the LEGO system, and in general these iterative prototype stages were not seen by the public. Some evidence suggests that it was normal to mould the prototypes in white - that way, they could be spray painted to whatever colour they wanted for prototyping concepts and themes.

Once the prototype element had reached its final form, the element was usually moulded in a variety of colours. At this stage, it could be used in promotional photography and for conceptual themes. In fact, one of the most reliable ways of identifying prototype moulds is by inspecting the boxes for LEGO products. Since the packaging had to be produced at the same time as the moulds being produced, they could not use the final production parts in many cases, and instead opted to use the prototype parts. This was of course only done when strictly necessary, and as such, prototype elements were almost exclusively seen in promotional photography during the year when that element was introduced for the first time.

One very important fact is that in internal development, there was no barrier between prototype elements that reached production, and prototype elements that did not reach production. A distinction has to be made to the public between prototype elements that did end up getting a produced form, and prototypes that never ended up released in any way.

Prototypes from before 1980 are incredibly hard to come by, and also hard to identify. The only known sign of early moulded prototype elements is that they should have no markings, apart from the LEGO logo. Unfortunately, many LEGO elements at the time did not feature any mould markings by default, and as such, one has to study a part very carefully against a huge sample size in order to figure out if a piece comes from a prototype mould.

Starting from the early 1980s, prototype elements often had specific markings that revealed that they were prototype elements. The oldest markings date to the early 1980s and are "LW" and "UV".

LW marking

LW is a marking encountered on certain prototype parts from the early 1980s. It is often paired with a design ID (part number) to denote the intended element number, that it would later take on if put into production. It is unknown what LW stands for. You can even see the LW marking on some transparent elements in box art, such as 6941 Battrax.

UV marking

UV is a marking encountered on certain prototype parts from the early 1980s. The UV marking is often paired with a design ID. It is unknown what UV stands for, but a guess is "Udviklings Version", meaning "development version" in Danish.

F.F. marking

In the mid 1980s, the F.F. marking starts appearing on some prototype elements, sometimes also abbreviated FF or with parts of the marking obscured. It appears to replace the LW marking. The F.F. marking is one of the most common prototype markings and stands for "Futura Form" and were moulds produced by LEGO Futura. The F.F. mark is also unique in that it is never seen paired with a design ID. As such, one can speculate that parts with the F.F. marking were never reserved a design ID. Interestingly, many of the elements bearing the F.F. marking are fairly generic in structure - such as a family of slopes or panels in various sizes, some of which were released. Highly specialized elements, such as minifig parts, rarely bears the F.F. mark.

In very rare cases, parts have been seen with the marking "FF2", which presumably is a second iteration after the prototype mould was "finalized", likely to resolve critical issues.

TF marking

In the mid 1980s, at around the same time that F.F. appears, the TF marking starts appearing on some prototype elements. The marking is essentially always paired with a design ID. The numbers of the design ID can commonly be seen being sloppy, flipped or incomplete. The earliest confirmed part with a TF markings date to 1985. The TF marking appears to phase out the UV marking, but the transition period is very unclear. This reportedly stands for "Teknik Form", which roughly means "technical shape". There is a lack of clarification here, but it is speculated that there was an internal department called "LEGO Teknik" that produced these moulds.

Some parts with TF markings have also been found with F.F. markings. It is unclear as to why, but since the TF parts have the design IDs, it is speculated that the F.F. mould is the previous iteration, and was then handed over to be finalized with the TF mould. It is even possible it is the very same mould just being re-tooled, and not a completely new mould.

In very rare cases, parts have been seen with the marking "TF2", which presumably is a second iteration after the prototype mould was "finalized", likely to resolve critical issues.

There have been observations where parts intended to work in pairs have had overlaps in terms of markings - for example an LW marking on the 2695 wheel, but a TF marking on the matching 2696 tire. This evidence suggests that the markings had a natural transition from LW to TF at some time in 1985 or earlier, before the pieces made it to production. It is also possible that there exist an earlier, unknown LW version of the TF tire.

Prototype elements without markings

Some parts during this era did still not have prototype markings. It is very difficult to authenticate such pieces without proper experience, but one can look for the following signs:

• The element lacks production markings, while the earliest known mould (01 mould) has clear production markings and a LEGO logo.
• The element looks rough or unfinished. This is commonly attributed to the prototype moulds rarely being polished.
• The element has a single, clear plastic injection point. Since prototypes were mostly moulded one at a time, it often leaves a big sprue that should match between all copies of the prototype element.
• The element has clear differences to the known production element, such as hollow studs being turned into solid studs and vice versa.
• The element is made out of LEGO plastic (remember to check with parts from the same era, as the composition of LEGO plastic varied a lot over the years).

Prototypes can sometimes fall outside of these criteria, but if the element does not have most of these properties, it is worth evaluating if the element is perhaps from another brand that also produces building blocks.

Prototype decorations

To rapidly prototype decorated elements, they were sometimes manually painted. Handmade prototype elements were commonly spray painted to transform them into the correct colour, and in order to prototype prints, employees would draw them directly on the elements. Very few of these prototypes have been found in public, and it's hard to draw conclusions from publicly available information and media. One example also exists of an element that has been spray painted another colour, and then printed on as if it was a regular part.

LEGO Design (2000-present)

After financial struggles, the pressure is on to find more effective ways of prototyping LEGO elements. The answer arrives at the turn of the century: 3D printing. While still in very early stages, 3D printing samples have been found dating back to 1997. At the time, 3D printing was a very rudimentary, but quickly got up to speed over the years. For the Bionicle product line, that launced in 2001, 3D printing appears to have been used both for prototyping elements, and also for 3D printing prototype moulds, to then mould with real plastic. By 2004, 3D printing has gotten accurate enough to completely phase out prototype moulds. This change also coincides with the LEGO Group's switch to a newer, cheaper "dyed" plastic. As such, any prototype moulds you encounter will likely only be in the older pre-mixed plastic.

The following decades, the LEGO Group rarely produced prototype moulds. Their 3D printing capabilities increase significantly as the technique gets better and better, and as they switch over to having renders on the LEGO boxes, the need for having moulded prototype elements that look close to the final product suddenly vanishes. Sometimes, when an element absolutely can't be 3D printed, it gets a prototype mould created for it, but it is always very limited, and sometimes even outsourced to another company.

In rare cases, 3D printed elements have been spotted in promotional material where physical sets have been photographed.

In 2024 (source?), the prototyping department at LEGO Design acquires a machine to allow for rapid moulded prototypes again.

Pre-production moulds

While the final production mould is being designed, it is continuously tested to evaluate the result. During this process, the mould can even be irreversibly altered if too much material is removed, or outright destroyed if an accident occurs, leading to the mould having to be re-made. Parts from this stage are very hard to come by, and should only ever have been produced at LEGO mould production sites.

LEGO Sets

LEGO sets go through several stages of prototyping before reaching a final product, and the process has varied a lot over the years. From the 1960s and onwards, the packaging for LEGO sets also started featuring product photos, which very often showed prototype versions of the LEGO elements. In recent decades, prototype iterations of LEGO sets simply use existing LEGO elements and only add novelty elements when the budget allows.

It is unknown how products were prototyped before the LEGO brick became the major focus of the company. The oldest known LEGO set that was prototyped, but never released, is the LEGO town plan zoo, prototyped in the late 1950s.

LEGO Packaging

LEGO packaging also has to go several stages of prototyping before reaching a final design. Prototype packaging is very rarely found, as it was only intended as temporary steps until the packaging was finalised, at which point the prototypes no longer served any purpose and was generally discarded. A few prototype boxes have been found with retailers, where they were intended to let the retailers plan out how to display the LEGO products on shelves before they were launched. Some items with preliminary packaging have also been found, often something given to people to test-run a product, and never intended to be sold.

LEGO Instructions

LEGO instructions is an iterative process that in the past required many tries to perfect. There were therefore a multitude of preliminary instruction sheets before they were finalised and ready for production. For a comprehensive history on LEGO instructions, please see the Instructions page.

Conceptual themes

In order to figure out what products to produce, the first step of a potential LEGO product line is to come up with a concept for a theme. These concept themes have commonly been mistaken for "unreleased themes" or prototype sets that never made it to production, but they are rather concepts that inspire a direction that a proper LEGO product line could go in. For example, the well known Sea-Tron concept theme was an evolution of a general "Underwater" theme, that developed into involving aliens. The theme kept evolving to take place on an alien planet, but only involving humans, and was eventually released as LEGO Aquazone in 1995. The colour scheme of Sea-Tron, green and black with trans-neon green elements, was later used in the Aqua Raiders theme in 1997.

This conceptual phase is often done in conjunction with prototyping new LEGO elements. There could, for example, be one employee who creates a dozen elements related to divers for a conceptual theme, that is then available to be used by any other employee designing sets or making concept themes. They then get feedback and iterate on these concepts until they reach something that they think can work, and move on to testing the concepts with kids. If the kids like the concept, it is approved for further development. In some cases, it can take more than a decade to go from initial concept to final product line (examples: LEGO Arctic, LEGO Aquazone). If the prototype parts used in the concepts appear promising, they can make it all the way to being produced as real elements.

A vast majority of conceptual themes were never put into production, and unfortunately documentation on these themes can be sparse. Most conceptual themes are also not available to the public, and only a few select themes are officially shown by the LEGO Group. There is a business interest in keeping these concepts secret, as they can still be used in future LEGO themes, or used in future LEGO media.

Unreleased items

LEGO items sometimes go through the normal production cycle, but for whatever reason, ends up not being put into production. Depending on how far along a product is when it's cancelled, it might be known to the public, or even be in the public's hands.

Cancelled items

There have been LEGO sets that were revealed in official media, yet never released officially by the LEGO Group. In most cases, it is not known why the sets were cancelled. Some examples include 8322 Mokarr, which was revealed in a Galidor retailer catalogue, but cancelled due to Galidor's poor sales, and the 6500 Holiday Village, which was intended to tie in with the LEGO Island PC game, but for an unknown reason was never put into production.

The list of cancelled sets will likely keep increasing forever, as unpredictable circumstances can change the reception of certain sets, and some recent examples include the 77014 Temple of Doom, and 71501 Game Island Tower.

Recalled items

The LEGO Group has had a few products that had finished production and is being sold on store shelves, but for whatever reason, is recalled. This is a very rare occurrence, and only a handful of LEGO products have ever been recalled. They technically do not count as unreleased items, but certain items have been recalled in between production and official release, which means there was existing stock of the product, which could have made its way to customers through pre-releases, or by stores selling products before they were intended to be sold. Some well-known examples include the 42113 Bell-Boeing V-22 Osprey, and the 21038 Las Vegas set.

Non-production elements

Certain items are created, but never intended to make it into the hands of the public. These are normally called non-production elements, since they are not intended for mass production.

Q-parts

During the 80s and 90s, the LEGO Group produced many of their elements in a multitude of colours for their LEGOLAND parks. These elements were sometimes retired without the element having a chance to be widely released in that colour, and as such, these elements were produced but never released. The name Q-part does not stem from a particular word, but instead means a "product code", where Q simply means an element is not meant for wider production or release, and instead was only produced in very limited quantities for the LEGOLAND parks.

Test moulds

To make sure that the moulds in the LEGO factories work correctly, they have to be tested. These tests are commonly done in specific LEGO colours in order to test for certain defects and shortcomings of the mould. Most commonly, elements are produced in red in order to show stress marks more clearly, but blue and green has also been frequently used. It is also common to use transparent colours, such as Trans-Clear, to test if the moulding process produces any internal bubbles, which might compromise the structure of the part and indicates the plastic injection isn't optimized. From the 2010s and onwards, test moulds have also been commonly observed in Light Bluish Gray. These test moulds can occur at any LEGO factory in the world.

Unprocessed factory stock

Many LEGO elements are not a single mould, but instead require several steps to assemble into a final LEGO element. It can involve several plastic LEGO elements (which each has its own unique design ID), involve non-plastic elements like electronics, or involve destructive processes, like drilling, gluing or cutting. If this process is interrupted, such as due to quality assurance, machine problems, or production ceasing, these unassembled elements can be left over from production. This also commonly results in unprinted elements, as some elements were only officially released with a print.

Factory rejects

When a LEGO element does not pass quality assurance, the entire bin containing the defective element is discarded in trash bins present in the LEGO factories. In rare occasions, these discarded LEGO elements have been recovered, either directly from the trash bin or during the recycling process, and made its way into the public's hands. Factory rejects are by nature never intended to make it into LEGO sets, and thus they are technically unreleased items. If the quality assurance process fails to catch it, a defective piece might end up in a retail LEGO set. In such cases, it is always possible to request a replacement by LEGO customer support, but you are of course allowed to keep the original defective element as a collectible. Factory rejects include: misprints, short shots and marbled elements.