Play-Doh

Play-Doh is a children's modeling compound made of wheat flour, water, salt, boric acid, and mineral oil. It was first made in Cincinnati, Ohio, U.S., as a wallpaper cleaner in the 1930s. Children began using it as a modeling compound. It was changed and marketed to schools in the middle 1950s. Play-Doh was used at an educational convention in 1956. Important department stores opened retail accounts. Advertisements on many children's television shows in 1957 brought more sales. Play-Doh has much spinoff merchandise, such as The Fun Factory. In 2003, the Toy Industry Association named Play-Doh in its "Century of Toys List".
Origin.
The non-toxic, non-staining, reusable modeling compound that came to be known as "Play-Doh" was a stretchy, putty-like substance made by Noah McVicker of Cincinnati-based soap manufacturer Kutol Products. It was made at the request of Kroger Grocery, who wanted a product that could clean coal residue from wallpaper. Following World War II, with the change from coal-based home heating to natural gas and the resulting decrease in coal soot, and the introduction of washable vinyl-based wallpaper, the market for wallpaper cleaning putty decreased quite a lot. 
McVicker's nephew, Joe McVicker, joined Kutol to save the company from bankruptcy. Joe McVicker was the brother-in-law of nursery school teacher Kay Zufall, who had seen a newspaper article about making art projects with the wallpaper cleaning putty. Her students enjoyed it, and she persuaded Noah McVicker and Joe McVicker to manufacture it as a child’s toy. Zufall and her husband came up with the name Play-Doh; Joe McVicker and his uncle Noah had wanted to call it "Rainbow Modeling Compound".