At HRL Laboratories in Malibu, California, materials scientist Hunter Martin and his team load a grey powder as fine as confectioner’s sugar into a machine. They’ve curated the powder recipe—mostly aluminum, blended with some other elements—down to the atom. The machine, a 3-D metal printer, lays the powder down a single dusting at time, while a laser overhead welds the layers together. Over several hours, the machine prints a small block the size of brownie.

Get in-depth coverage of current and future trends in technology, and how they are shaping business, entertainment, communications, science, politics, and society.

Advertisement