So far, the biggest benefit of 3D-printing organs is that you don't need someone to donate their body to medical science before you can do an experiment. That's why Organovo's big news is so exciting for scientists, since the company has let it be known that its 3D-printed livers are now on sale. The bio-printed tissues can be used for drug testing programs, since causing unexpected liver damage is one of the biggest causes for pharmaceutical recalls. Unfortunately, with a rated lifespan of around 42 days, we won't be able to use these stamp-sized organs in transplants just yet, but who knows? Maybe in a few years time, the idea of asking a relative or close friend for a slice of their liver will be as outdated as sending them a fax.