André Cassagnes: inventor of Etch a Sketch

Wiki.answers relates an interesting story:

André Cassagnes, an electrician at Lincrusta Company, conceived of the idea of a mechanical drawing toy using aluminum powder in a sealed case.

BUT

He was directed to Paul Chaze, the owner of a plastic injection molding company named MAI.

Chaze agreed to fund development of the device as well as helping Cassagnes to officially register his patent. Chaze instructed his accountant, Arthur Granjean, to prepare, file and pay for the patent on the "tracing device". The patent application was submitted 28 May 1959, without Cassagnes' knowledge and under Granjean's name. MAI produced some prototypes and then licensed the design to a French company, Joustra, which produced it under the name "Telecran" (the name that Cassagnes used for the toy) and paid Cassagnes a royalty.

AND
Chaze and Winzeler [of Ohio Art] met with Cassagnes. Cassagnes agreed, reluctantly, to relinquish all rights to the invention, and all future royalties (except in France), for the sum of $10,000.

Over the course of the next 18 years, Ohio Art paid over $1 million in royalties to Chaze.