Rapid Prototyping (RP) – technology allows 3D-printing of arbitrarily shaped structures, directly from computer-aided design (CAD) data. It has traditionally been used to produce only passive mechanical parts. A team at Cornell University has developed compact, automatic Solid-Freeform Fabrication systems, or “fabbers”, which can build almost any kind of object – not merely passive mechanical parts, but complete devices, ready to use right out of the machine.