Safety Pin: The Three-Hour InventionPaying off a debt with a piece of twisted wire

From the show

The Secret Life of Objects

Walter Hunt was a prolific inventor who owed a friend $15 and had no way to pay it back. Desperate, he picked up a piece of brass wire and spent three hours twisting it until he created a clasp that wouldn't prick fingers. He sold the patent for $400, clearing his debt but losing millions in potential royalties.