"In 1962, Englishman Denys Fisher was a mechanical engineer, using his expertise with NATO to design improvements in bomb detonation equipment. Using interlocking gears and the point of a pen, Fisher hoped to trace sine and cosine waves by using the gears as a moving stencil. Originally Fisher wanted to market his spiral graphing product to industrial companies, but could find no takers. His family, however, found another use for Fisher’s invention – as an educational toy.
Eventually Fisher’s gear-inspired doodles became the “Spirograph” kit, and when Fisher introduced the kit at the 1965 Nuremburg International Toy Fair, toy industry officials came calling. Kenner Toys purchased the rights to Spirograph for American consumers, with Fisher receiving U.S. Patent No. 3230624 in January 1966." -Source