Toys that were originally invented to do something else.
Slinkys, playdoh, paintballs...
all were invented and used for other things.
But silly putty? Trying to find a substitute for natural rubber, but no one could find a use for the stuff, except that the lab people liked to play with it..
.Earl Warrick of Dow Corning and James Wright of General Electric. Working independently on crafting a rubber substitute, the men discovered that combining boric acid and silicone oil produced a bouncy, elastic putty with a high melting temperature. Unfortunately, while this bouncing putty entertained the lab workers, it wasn’t the viable rubber substitute needed for the war effort. Wright sent samples to scientists around the world to see if they could find a practical purpose for this new substance, but no one could.