3D printing, rapid prototyping, as it is often known, is not new. I first heard about 3D printing sometime in late 1980s while still a student. However, these devices, which have featured in TV shows such as CSI, could soon be coming to a workshop near you and may represent the biggest shift in commerce and manufacturing in decades. The Fab@Home wiki has more information on the technology, but 3D printing, essentially, turns a digitized representation of a solid object, which you might download, email, or create, into a real solid object. It using a vat of uncooked starting material (plastic, metal or alloy) and a laser, or other device, controlled by computer holding the digitized information to build up the object layer by layer.

Source: www.sciencebase.com