An interesting innovation of modern times is deposition printers, which can produce any 3 dimensional object by laying it down layer by layer in melted plastic, which rapidly cools and solidifies into a layer of the final object. If an layer can't support itself structurally until complete, the system can also lay down a second type of plastic that washes away when exposed to water. Although the systems tend to be expensive (none cost less than $500), once you own one, you can have all the plastic parts you want for a few cents worth of thermoplastic.
Medical doctors have especially taken note. Human cells can be grown in a lab, but only in flat sheets about one cell thick. The cells know that they shouldn't endlessly grow upon each other, because when they do that, they're typically cancer. Cells in your body grow on a framework, an extracellular matrix. And here's where they have the idea.
Since the 3d printer can print any shape, have it print an extracellular matrix for an organ, wash it, and introduce it to a glucose-and-saline medium. Inject one human cell, and a short time later, you have a fully functional organ. Since extracellular matrix parts are regularly replaced, this new organ will, after being implanted, slowly replace its plastic extracellular matrix with a real one, at which point the organ will be indistinguishable from the original. Other than the new one is fresh and healthy and will last for years longer.
This is giving me an even crazier idea, which I will go into tomorrow.