Since 1963, Lego pieces have been manufactured from a strong, resilient plastic known as acrylonitrile butadiene styrene (ABS).[12][30] As of September 2008, Lego engineers use the NX CAD/CAM/CAE PLM software suite to model the elements. The software allows the parts to be optimised by way of mould flow and stress analysis. Prototype moulds are sometimes built before the design is committed to mass production. The ABS plastic is heated to 232 °C (450 °F) until it reaches a dough-like consistency. It is then injected into the moulds at pressures between 25 and 150 tonnes, and takes approximately 15 seconds to cool. The moulds are permitted a tolerance of up to twenty micrometres, to ensure the bricks remain connected.[33] Human inspectors check the output of the moulds, to eliminate significant variations in colour or thickness. According to the Lego Group, about eighteen bricks out of every million fail to meet the standard required.[37] Lego factories recycle all but about 1 percent of their plastic waste from the manufacturing process. If the plastic cannot be re-used in Lego bricks, it is processed and sold on to industries that can make use of it.[38][39] Lego has a self-imposed 2030 deadline to find a more eco-friendly alternative to the ABS plastic it currently uses in its bricks.[40]
The capabilities of the Mindstorms range have now been harnessed for use in Iko Creative Prosthetic System, a prosthetic limbs system designed for children. Designs for these Lego prosthetics allow everything from mechanical diggers to laser-firing spaceships to be screwed on to the end of a child's limb. Iko is the work of the Chicago-based Colombian designer Carlos Arturo Torres, and is a modular system that allows children to customise their own prosthetics with the ease of clicking together plastic bricks. Designed with Lego's Future Lab, the Danish toy company's experimental research department, and Cirec, a Colombian foundation for physical rehabilitation, the modular prosthetic incorporates myoelectric sensors that register the activity of the muscle in the stump and send a signal to control movement in the attachment. A processing unit in the body of the prosthetic contains an engine compatible with Lego Mindstorms, the company's robotics line, which lets the wearer build an extensive range of customised, programmable limbs.[54][55]

Since around 2000, the Lego Group has been promoting "Lego Serious Play", a form of business consultancy fostering creative thinking, in which team members build metaphors of their organizational identities and experiences using Lego bricks. Participants work through imaginary scenarios using visual three-dimensional Lego constructions, imaginatively exploring possibilities in a serious form of play.[73]