Class 2 article

Modulex was a building system that was designed for adults. It was developed by The LEGO Group at the same time as their Modulex sets were produced from 1963 until 1965, and were exclusively available in parts packs by colour. The LEGO Group made Modulex a separate company in 1965, and the text "LEGO" was removed from the studs and replaced with "M".


Modulex comparison

Comparison shot. On the left, Modulex, on the right, a System brick.

Modulex bricks were formed with a cube type 5 to 5 width/length ratio, meaning that, unlike very nearly every product produced by The LEGO Group, they were not compatible with LEGO bricks, which have a 6.5 to 5 width/length ratio. Modulex bricks were available in a wide array of unusual colours, shapes, and sizes.



The idea for the Modulex brick came at an unknown time in the early 1960's, when Godtfred Kirk Christiansen was attempting to create a model for the house he was building out of LEGO bricks. To his surprise, he found he was unable to do it accurately, as LEGO bricks had an aspect ration of 6:5, rather than the European standard of 1:1. Rather than build his model out of scale, Godtfred had a uniquely sized line of parts moulded for him, that would allow him to copy his plans more exactly.

After some thought, Godtfred realised that LEGO bricks in this size developed specifically for architectural planning and modelling might actually be a successful and commercially viable product, and so Modulex was born.


Through an unusual coincidence, at the same time when Modulex was being designed, the Architecture System of sets such as 750 Hobby and Model Box, 751 Hobby and Model Box, and 752 Hobby and Model Box were released. Despite the similarity of premise and release date, there is no definitive proof of a connection between Modulex and Architecture.

Marketing Under LEGO, and The M20 System

First off, LEGO created a subsidiary company, Modulex A/S (although the name is reported to vary), specifically to sell Modulex products, the first of which, the "M20 System", was released in 1963.

The system consisted of a series of bricks including everything from windows to simple 2X4s and slopes, in addition to several more unusual items, such as unique baseplate foil, foil combs and cutters, and, uniquely for LEGO, solvent-based glue to stick models together after construction.

The line was intended for building in 1:20 scale (hence the name M20). M20 sets were available mainly in sets containing an assortment of bricks, but they were also available in bulk.

Due to changing architectural designs of the time that could not be recreated with Modulex, the higher price of the system in comparison to the traditional materials used for models and, at worse, possible perceived unprofessionalism in using a 'children's toy' for model building, M20 didn't do very well with architects, who were, after all, the target audience, but it had became quite popular with industrial planners. So, in 1966, Modulex split into a separate company from LEGO (although they were still owned by the group), and released the Modulex Planning System, specifically designed for use by this demographic. In this use case, Modulex was used for planning out interior areas, such as an office floor or factory area, and large scale planning like placement of buildings in cities or city sections.

After LEGO

The Modulex Planning System, featuring bricks rebranded with an "M" logo on the studs, included plates, tiles, and blocks with letters printed on them.

After several further years of producing bricks, Modulex underwent a major change with the release of Interior 10, an architectural signage system. Although based on some of the ideas of the Planning System, Interior 10 and the 1979-introduced Exterior 500 finally brought the company away from the ideas of LEGO entirely.

In 1993, Modulex merged with ASI Sign Systems, and is currently the most successful signage company in the world, with subsidiaries in more than thirty-five countries. However, the LEGO-style planning system was not entirely forgotten, with Plancopy, introduced in 1982, and updated in 1994. Plancopy is still available to this day.

Modulex Brick Colours[]

Common Colours
Rare and Unique Colours


External links[]