3D printing is one of a number of technologies that have bloomed and spread across the world incredibly rapidly in the last decade. Prosthetics for amputees, rocket parts, and bridges have all been built using 3D printers, and recently, researchers demonstrated how to print out the structures for human organs using biological material. This month, a new study in the journal Biofabrication has described the process of 3D printing stem cells’ “building blocks” for the first time.