In 1959, John Dos Passos took a break from writing to invent a bubble gun, presumably for his 9-year-old daughter, Lucy:

The primary object of this invention is to provide a bubble toy in the nature of a pistol … upon squeezing the hand grip air is forced … toward the ring, causing bubbles to be formed from a film held by the ring, and the bubbles projected forwardly as bullets from a gun.

After this he went back to the typewriter — Prospects of a Golden Age was published in the same year.