Pig lung transplanted into a human

3d printing is not the approach that will yield organs. My money is on the work Michael Levin is doing on bioelectronics, where you essentially “command” (/convince) cells to turn into the organ you need by talking with them in cellular electronic language.

My mind-reading senses tell me parent might be thinking about the scaffolding approach where you show cells the vague outlines of a lung or heart in the form of an extracellular matrix and then they go "hmm, we are building a heart then".

If I remember correctly you need both. Program the cells to be X organ cells, and provide a scaffold for them to grow on.

that seems like a way harder problem than convincing your body not to kill the pig organ