If the thought of robots permanently marking your body is too much to imagine stop reading now. A 3D printer has been hacked to ink tattoos onto people and it was done using a printer you can buy.
Appropriate Audiences is a French company which hacked the MakerBot printer to make it a tattoo artist. The machine, dubbed Tatoue, was originally created to follow lines drawn on a person's skin allowing you to draw a tattoo in pen and have it inked permanently by the machine. Now the machine can use design files too.
Users can upload any design they want, place their arm in the printer, and the machine will do the inking. This is an interesting area to use a machine as some might argue it could be more accurate than a human artist. Though will it imbue the soul?
Presumably the machine could also be adapted to print with less permanent ink allowing people to test out designs on their skin before deciding to go permanent. So rather than putting tattoo artists out of work it could act as a complimentary device to help their customers find the perfect design.
Tatoue is part of a design project at the moment so it won't be going on sale but if you're committed enough you could probably modify a MakerBot yourself, probably.