3D printers are a way of producing a 3D model of an item from a digital file. The model builds up in successive layers of material placed by the printer controlled by the information in the computer file. In this article the author argues that 3D printers are one of the greatest technological advances of recent times. He discusses practical uses of the printers, in-school applications, cost implications, using the software, and the impact the 3D printer had on his year 3 (ages 7-8) and 5 (ages 9-10) students.