On the materials graph, I was surprised to see "biomaterials", so I looked it up. I had no idea 3d printing was being used to build human organs. This is amazing :S
"As of 2012 3D printing technology was being studied by biotechnology firms and academia for possible use in tissue engineering applications where organs and body parts are built using inkjet techniques. Layers of living cells are deposited onto a gel medium and slowly built up to form three dimensional structures. Several terms have been used to refer to this field of research: organ printing, bio-printing, and computer-aided tissue engineering, among others.[21] 3D printing can produce a personalized hip replacement in one pass, with the ball permanently inside the socket; at available printing resolutions the unit does not require polishing."