Eighteen months ago, design students Pierre Emm, Piotr Widelka, and Johan da Silveira decided to turn a MakerBot 3D printer into an automated tattoo artist. They replaced the printer’s extruder with a tattoo gun and added a haptic sensor to detect variations in the skin’s surface. To translate tattoo flash art into digital files, they modified the Autodesk design software that is often used with 3D printers. Guided by computer-aided design, the printer successfully inked a circle--which the designers consider the perfect shape to test precision--onto a human arm in October 2013. Their company, Appropriate Audiences, plans to bring a consumer version of the machine, called the Tatoué, to market in 2016.