3D printing—a manufacturing technique by which objects are built from digital data in a way analogous to how computer text is printed on a page—has captured the imagination of many with its potential to offer flexible, inexpensive manufacturing for widespread use. 3D printers have been used to build everything from rockets to houses to guns to other 3D printers, their capabilities limited only by access to a low-cost 3D printer, a set of digital blueprints, and some ingenuity.