Never mind 3D-printing organs — eventually, the material could have a life of its own. Phys.org reports scientists have developed a "living ink" you could use to print equally alive materials usable for creating 3D structures. The team genetically engineered cells for E. Coli and other microbes to create living nanofibers, bundled those fibers and added other materials to produce an ink you could use in a standard 3D printer.
Researchers have tried producing living material before, but it has been difficult to get those substances to fit intended 3D structures. That wasn't an issue here. The scientists created one material that released an anti-cancer drug when induced with chemicals, while another removed the toxin BPA from the environment. The designs can be tailored to other tasks, too.
Any practical uses could still be some ways off. It's not yet clear how you'd mass-produce the ink, for example. However, there's potential beyond the immediate medical and anti-pollution efforts. The creators envisioned buildings that repair themselves, or self-assembling materials for Moon and Mars buildings that could reduce the need for resources from Earth. The ink could even manufacture itself in the right circumstances — you might not need much more than a few basic resources to produce whatever you need.