3D printing
Johannes F Gottwald patented the Liquid Metal Recorder
Alexandria, Virginia, U.S.
In 1971, Johannes F Gottwald patented the Liquid Metal Recorder, US3596285A, a continuous Inkjet metal material device to form a removable metal fabrication on a reusable surface for immediate use or salvaged for printing again by remelting. This appears to be the first patent describing 3D printing with rapid prototyping and controlled on-demand manufacturing of patterns.