Play-Doh: Did you know that this was originally invented in the 1930′s as a wallpaper cleaner? It didn’t become an official kids’ toy until 1958. Can you imagine all of the annoyed moms searching in vain for their wallpaper cleaner blob, only to find it being molded into a dog by little Eddie? No, me neither. To date, 700 million pounds, or 2 billion cans of Play-doh have been sold.