LEGO® Prototypes: What Goes on behind the scenes.

Unfortunately for fans, LEGO® chooses to remain quite secretive with what goes on in their factories and design studios. It's through factory prototypes that we can gain a glimpse of how exactly LEGO® operates.

The Famous Red Prototypes:

If you're familiar at all with rare LEGO®, you've likely seen your fair share of Red prototype parts. According to several LEGO® employees, the color red is the most vibrant under factory lights making it easy to spot production flaws. Thus, LEGO® is said to produce every new mold in red before sending the piece into production. The value of these parts range drastically from only a couple dollars, all the way up to thousands per piece. The year, theme, and intricacy of the piece tend to cause these disparities in pricing. A majority of the most expensive red prototypes currently available are pieces from the original Star Wars waves of 1999-2002, though these red prototypes are said to date back as early as the 1960s. It should be noted that prototypes do not only appear in red, colors like grey, blue, and green can also be found, though those are more common in non-minifigure parts.

Numerous Red Minifigure part Prototypes

Various Star Wars Minifigure part prototypes

The Castle Ghost in 4 prototype colors

Unreleased Minifigures:

Before LEGO® releases a figure, the production process must start months or even years in advance. When changes in product line success, public drama, or internal roadblocks prevent the release of planned sets, these initial test figures remain dormant. While generally destroyed or kept in LEGO® storage, some never-released minifigures surface on occasion. Some examples include the Knights Kingdom 3 prototypes, Overwatch's Mei, and the original Seatron figures. (See photos below respectively). The prices they command depends heavily on how far in production the figures got, how many copies were made, and the popularity of their respective theme. Figures like Mei from Overwatch can be acquired for less than 500 USD, whereas the Seatron prototypes sell for thousands when available.

Knights Kingdom Unreleased Minifigures

Seatron Prototype

Unreleased Mei from Overwatch

Pre-ABS production parts:

While those prior prototypes are certainly unique and expensive, some parts are a bit closer to being priceless. At the very first stage of production, LEGO® prototypes are created using other methods of construction. Numerous intricate methods include R&D include Sterolithographic 3D printing, Selective Laser Sintering, and even Precision woodworking. These advanced methods require extreme care and can create tolerances of less than 0.005 Millimeters. Or 0.0002 inches.

Stereolithography (SLA):

Usually known more simply as Resin Printing, this extremely pricise form of 3-D Printing is most commonly used for modern LEGO® mould prototypes. It works in quite a remarkable way. A microscopically small DLP (Digital Light Processing) Laser is positioned facing upward into a vat of Liquid Polyurethane elastomer. A base is situated upside down within the liquid, equipped to a Z-axis Mechanical Gantry, moving the base upwards as the print ensues. A CAD (computer aided design) file is uploaded to the system and DLP itself moves over the 2d Axes. This triggers a photochemical reaction that uses 405nm UV light to overlap the Polyurethane monomers and oligamers. This creates microscopic solids (15-50 microns) know as Voxels. This process is repeated millions of times per second as the 3 gantries move simultaneously, creating a solid object.

NINJAGO serpent SLA prototypes

Queen Amidala SLA prototype

Mickey Mouse SLA prototypes

Selective Laser Sintering (SLS):

Similar to SLA, SLS is a specialized type of 3-D printing which, unlike plastic or resin, works with a specialized plastic nylon powder. Beneath the bed of powder lies a low-powered Carbon Dioxide (CO₂) laser. Like SLA, this laser chemically binds the nylon polymers to create a solid structure. A CAD (computer aided design) model of the desired piece is inputted and the machine outputs a prototype, often larger than thr real figure to show intricate details. SLS prints, despite their powder construction, tend to outperform SLA and standard 3-D printed parts.

SLS NINJAGO headgear prototypes

SLS and SLA / Polyjet NINJAGO Skeleton Prototypes

SLS Star Wars Stormtrooper Helmet Prototype

Carving/Sculpting

Though rare now, it was once fairly common for LEGO® designers to carve early prototypes from blocks of wood or sculpt them from clay. These methods led to a more rough and unpolished prototype. These methods were used mostly pre-2000s, with some of the original Star Wars figures having sculpted prototypes. While images of all original prototypes are difficult to find, these ones are especially so.

Vintage Wooden LEGO® Brick Prototypes

Preliminary space prototypes

Early wooden axle prototypes

Polyjet production:

Polyjet is a very similar process to SLA, though the difference is in the operation of the liquid. Instead of a vat of Polyurethane, it is sprayed through a fine tip and cured with the same UV light. The double gantries, both Z, and XY are still present, allowing for efficient printing. This method produces a very similar result to SLA, without the need for so much Polyurethane.

A polyjet Sebulba Prototype (left) from Star Wars 

Polyjet Nexo Knights prototype

Alien Conquest Polyjet Prototypes

Finding Pre-ABS Prototypes:

These prototype are exceedingly rare for 3 reasons. Firstly, there are never more created than necessary, some Minifigure parts only have one, while more intricate pieces may have 4 or 5, though each is generally unique and displays a different design than the previous. Secondly, because LEGO® design employees work on so few figures over their tenure, they are often quite fond of their work, electing to keep their prototypes as mementos to their production. Lastly, these prototypes are seen as ultimate collector pieces in the community, prompting those with them to refrain from selling. I myself have reached out to several individuals in possession of these prototypes, only one of which was willing to even consider an offer.