Tennis-Ball Hopper

Its invention made quick work of a tiresome chore

In the 1960s, Jake Stap ran two tennis camps, where he spent way too much time gathering the tennis balls scattered around the courts. “That was the bugaboo— getting the kids to pick up the balls,’’ said his daughter, Sue Kust.

One day, driving to his job as a gym teacher in Illinois, USA, Stap pinched the ball that was rolling on the seat beside him. The rubber yielded under his fingertips.