The 3D printing of bone. We haven't quite been able to do this yet, however researchers are certainly coming quite close. Researches have found a new way in which they can print using calcium phosphate, one of them main ingredients of a human bone, in a way which also allows them to add bone growth drugs, antibiotics, and human cells to the equation. The full details of the report can be found here: http://3dprint.com/8283/3d-printed-bone-grafts/

This could certainly one day in the future allow for surgeons to just 3D print custom fitted human bones for people, prior to surgery. Opinions?