For years, the potential of 3D printing has made tech geeks drool, but now we're finally starting to see the technology graduate from a mere novelty into a highly useful tool. Take, for example, the story of the 5-year-old boy who was born without fingers on his right hand but recently received a 3D-printed prosthetic hand. Thanks to its quick turnaround speeds, the technology also enables scientists to test multiple designs at once. For example, in Australia researchers are using 3D printers to produce more effective tags that can be used to track large fish. At Cornell University, researchers are experimenting with using 3D printers to print food that could be eaten by astronauts in space, and scientists in Edinburgh successfully 3D-printed embryonic stem cells for the first time, demonstrating how 3D-printing technology could one day eliminate the need for organ donation. In related news, scientists were recently surprised to find children's cells living in mother's brains long after pregnancy.