Thomas Edison’s 1876 electric pen was designed to make copies of writing with a stencil.
The electric pen used a small motor to drive a needle rapidly up and down. As a person wrote, the needle perforated a stencil sheet with tiny holes. Ink could then be pressed through the stencil to produce multiple copies of the original document.
The device was one of Edison’s early commercial inventions and reflected his interest in office technology as well as electrical systems. It was later adapted into stencil-duplicating equipment, although it did not become as successful as Edison’s best-known inventions.
The electric pen is often confused with the mimeograph itself. Edison’s pen created the perforated stencil; the broader duplicating process used additional equipment to transfer ink through that stencil. The invention also influenced later tattoo-machine designs because its reciprocating needle mechanism resembled the action needed to insert pigment into skin.