The principles of 3D printing are being applied to medicine, raising the possibility that doctors might someday be able to produce human organs for transplant and end the use of waiting lists. California biotech company Organovo already has a prototype of the so-called "bioprinter," which uses two printer heads to place cells ("bioink") onto a water-based gel ("biopaper"). For more details on the process, see the Telegraph and, especially, the Engineer.
“Ultimately the idea would be for surgeons to have tissue on demand for various uses," says Organovo's chief executive. (More organ transplants stories.)