3D printing of organs is becoming more and more a reality with researchers fine tuning the process. Scientists are presently trying to tackle the best ways to print a wide range of tissue & cells types. Bone appears to print & grow best within a hydrogel scaffold. Cartilage, on the other hand, appears to grow best just on its own without a scaffold. Imagine how wonderful it will be when doctors will be able to order new printable organs for transplants surgeries!
Resources: Savage, Neil. "The promise of printing". Nature. 2016. pS56-7.