Answer: Tattooing

In 1876 Thomas Edison filed a patent for the “Stencil-Pen”. This rotary-engine driven pen was intended to semi-automate the process of duplicating print and artwork by using stencils combined with the ink-loaded reciprocating needle that served as the pen tip. The needle punctured the paper 50 times a second and impregnated the paper with micro-drops of ink.

While the Stencil-Pen was ultimately a commercial failure in the arena of print duplication, it became a commercial success in the arena of body modification. In 1891, Samuel O’Reilly expanded on Edison’s design to serve as a tattoo artist’s tool–injecting micro-droplets of ink under skin instead of into paper. Although tattoo machines have undergone many changes since then (such as replacing the rotary mechanism with an electromagnetic coil) they can all trace their ancestry back to Edison’s Stencil-Pen.

Bonus Trivia: The Stencil-Pen was the first electric-motor driven appliance sold in the United States.