How Things Work: Legos

Legos. We have all played with them. For decades, these tiny blocks of plastic have inspired children and adults alike to rip open a bag and unleash their artistic creativity.

Lego kits exist for almost everything under the sun. There are kits for Lamborghinis and kits for mythical creatures. There are kits for missions to Mars (the Mars Mobile Mining Unit will collect Mars samples, but only after reporting to the Mars Eagle Command Base) and kits for Claw Crushing machines used by the Iron Drones. There is a kit for The Indiana Jones Motorcycle Chase.

New kits, like Lego TECHNIC and Lego BIONICLE, allow you to build Lego bulldozers with pneumatic cylinders and breathe life into action figures like Hakann, Toa Nuparu, and Zaktan.

There are even companies dedicated to the sale of life-like Lego products. BrickGun ( is a website that specializes in selling state of the art weapons, like the IMI Desert Eagle and the Beretta 92FS — made entirely of Legos.

Despite its sophistication, the underlying components of a Lego masterpiece are surprisingly simple.

The standard Lego piece is a 2x4 multicolored brick. The dimensions can vary between pieces, and can be found by counting the number of studs (or bumps) along either side. Other basic Lego elements include the peg, plate, and beam.

Legos begin as multicolored granules. The granules are made of acrylonitrile butadiene styrene (ABS), a thermoplastic material commonly used for molding and shaping because it melts to a liquid when heated. The granules come in eight basic colors: red, yellow, white, blue, black, dark grey, light grey, and green.

The granules are loaded onto a truck and taken to a Lego factory. At the factory, the granules are siphoned out of the truck and showered into a three-story tall metal silo. A mountain of Lego granules resembles a mound of salt or sand in appearance — except that the constituents are tiny pieces of plastic.

Each silo holds 33 tons of Lego granules.

Once in the silo, the granules are fed into a molding machine through a large pipe. Here, the granules are heated to 450ºF. The extreme temperatures are required to melt the plastic granules and force them into a molding apparatus.

Inside the molding apparatus, 150 pounds of pressure are applied to shape them into the familiar pieces we see in toy stores and children’s bedrooms. Since the slightest deviation in size destroys a Lego’s “snap and bind” ability, the molds have a precision tolerance of 0.002 millimeters. The molding machinery is so precise that only 18 out of every 1 million Lego bricks produced are considered faulty.

At any given moment, 2.16 million Lego components are being molded around the world. This translates to about 19 billion Lego bricks a year — roughly the GDP of Burkina Faso.

After several seconds of applied heat and pressure, the newly minted Lego pieces are ejected from the mold and tossed onto a conveyor belt, where they are allowed to cool. At the end of the belt, the pieces are dumped into a large box. Once the box is filled, it is picked up by a robotic truck and taken across the factory to the assembly hall.

Here, the Lego pieces are decorated and stamped. Minifigs, the miniature figures that have become a hallmark of any Lego set, are also assembled and designed, with great precision, in the assembly hall. The finished pieces are then packaged into kits.

Today, children spend 5 billion hours a year playing with Lego bricks. A Chrysler building replica stands tall at the Times Square outlet of Toys “R” Us, in New York City.

Despite its worldwide popularity, the Lego brick has humble origins.

In 1932, Ole Kirk Christiansen, a Danish carpenter on the brink of bankruptcy, started selling wooden toys from his workshop to make extra money. Eventually, Christiansen named his company “Lego” — an amalgamation of the Danish words leg godt, meaning “play well.”

Four hundred billion Lego bricks have been produced since 1949. If the amount of Lego bricks sold in a given year were placed end-to-end, the line would circle the Earth five times. The Lego brick itself also holds a U.S. Patent.

With Lego obsession come Lego artisans, like Nathan Sawaya, who has created, among other projects, an eight-foot tall Lego pencil and a replica of the flag raising at Iwo Jima. Sawaya is touring museums around the country with an exhibition called The Art of the Brick. Sawaya gave up a lucrative career in law for a life of Lego. His artwork can be viewed on his website,

Andrew Carol built a Babbage difference engine No. 2 — a calculating machine — entirely out of Legos.

The machine, along with a complete description of its interior, exterior, and computational capabilities by Carol, can be viewed at