One innovation in 3D printing is the ability to recreate a realistic but artificial human body, or a partial body, for a particular surgical patient. A medical scanner maps out the size, shape, and positions of organs, and then an exact copy is manufactured, as demonstrated here by the company Lazarus 3D. That's for surgeons to practice on, to avoid that moment when they cut a person open and find surprises. A sort of dress rehearsal for the actual surgery. Tom Scott volunteered his body for the demonstration, and the scan revealed he luckily didn't need surgery, so they added a cyst just so we could watch them remove it.