The best-known toy brick maker is the LEGO company, which is based in Billund, Denmark (as of November 2026). The name LEGO comes from two Danish words, leg godt, which mean play well. The word lego also means 'I put together' in Latin, a coincidence the company noticed later.

The company started in 1932 as a small carpenter's shop in Billund. Before plastic bricks, the shop made stepladders, ironing boards and wooden toys. LEGO acquired a plastic injection-molding machine in 1947, the first in Denmark. Plastic was chosen partly because it was easy to clean and came in many colors and shapes. Kiddicraft, a British company, had sold interlocking plastic bricks with studs before LEGO did.

LEGO began making Automatic Binding Bricks in 1949. These first plastic bricks had no tubes inside, so they did not hold together as well as later ones. Sales were weak too. In the early 1950s sales of the plastic toys were mediocre, customers preferred wooden or metal toys, and many shipments were returned. In 1958 the tubes were added, and the 1958 tube design is credited with turning sales around. The man who thought of the tubes was Godtfred Kirk Christiansen, the founder's son.

A toy brick has bumps on top and is hollow underneath, so it snaps together. Toy bricks stick together because the studs on top fit tightly between the tubes inside another brick. The tubes make the bricks grip each other, which LEGO calls clutch power. Clutch power is the force needed to pull two bricks apart. It is measured in newtons, and LEGO keeps the exact ideal number secret. Many bricks have tubes inside, but pieces one stud wide use a thin bar instead.

Toy bricks are made from tiny plastic grains called granules, stored in giant tanks called silos and sent to the machines through tubes. Color is added at the machine, so one plastic can make bricks of many colors. Hot plastic is injected into one side of the mold, spreads through little channels and fills the brick-shaped space. Cold water flows through the mold to cool the plastic, then the mold opens and the bricks drop onto a belt.

The plastic used for bricks is called ABS, which stands for acrylonitrile butadiene styrene. ABS is a thermoplastic: it softens when heated, so it can be melted, shaped in a mold and cooled hard again. It is a tough, strong plastic that can survive being dropped, and it can take any color and have a glossy finish. The earliest LEGO bricks were made of a wood-based plastic called cellulose acetate, until the company switched to ABS in 1963.

LEGO had a quality control department of 13 people by 1963, and 'only the best is good enough' has been its motto since early days. Machines weigh each box, and any that are too light or too heavy are flagged so a person can check them. Machines also count the pieces that go into each box using light sensors, and pieces for sets are put into small bags.

When a collection bin under a molding machine fills, the machine signals a robot, which drives down the aisle on its own, takes the full box and leaves an empty one so production resumes. In the Billund factory eight robots moved 600 bins per hour, according to a 2016 report. In 2008 a reporter counted about 19 billion bricks a year coming out of the Billund factory.

Bricks that have faces or patterns get them printed or stamped on by machines. Decorating, such as painting faces and patterns, is the most expensive part of making a LEGO piece.

A 2011 report found that almost all the plastic in a LEGO factory was reused: scrap from the molds was ground up and fed back in. Faulty pieces and the clear plastic used to flush a machine between colors were ground up and sold on.

Even so, most LEGO bricks are made of ABS, an oil-based plastic. Plastic that is thrown away does not rot away like food or paper: it can stay around for hundreds of years.

LEGO says it is looking for other materials and wants to make its products from more sustainable materials by 2032. It unveiled a prototype brick made from recycled plastic drink bottles. After two years of testing it chose not to use it, because it would not have cut carbon emissions. By 2023 LEGO had tested more than 300 different materials, and some worked better than others. Bricks are built to be taken apart and built again, and new bricks still fit bricks made since 1958.

Words to know

• clutch: grip strength
• granules: tiny plastic grains
• thermoplastic: plastic that melts
• silos: giant storage tanks
• prototype: first test model