With hardware and techniques borrowed from offices and factories, researchers are taking the first steps to biologically engineer replacement body parts from a patient’s own cells. If successful, they could one day grow joints, bone, skin and even complex organs like the cornea. Many of them are working with inkjet printers, one of the staples of home and office life. Instead of ink, the printers are charged with solutions containing human cells, which are then deposited onto a growth medium. Several studies have shown that the cells survive the printing process, so researchers are now looking further ahead, building three-dimensional structures layer by layer.