Play-Doh began life in the 1930s as a rather unexciting wallpaper cleaner. When coal furnaces left soot on household walls, the soft putty could be rolled across the wallpaper to lift off the grime.

As cleaner heating systems made sooty walls less common, the product seemed destined for the dustbin. Then, in the 1950s, nursery-school children began using it to make decorations and models. The cleaner was reformulated, brightly colored, renamed “Play-Doh,” and marketed as a toy.