From NPR: Fetch 2.0: Man Builds Machine for Dog:

The Bryant Park Project, May 8, 2008 · Lam Ngo needed a way for his dog, Jerry, to get exercise while the software engineer was away at work. The dachshund loved playing fetch — so much so that Ngo often spent hours tossing the ball for him.

Despite having never made a machine, Ngo set out to invent one that Jerry could use to play fetch all by himself. Ngo, of Cary, N.C., says he spent two years tinkering with parts cannibalized from various machines before hitting on the design for what he calls "Jerry's Ball Machine."

The launcher's key parts include an assembly head from a dot matrix printer, which makes the ball fly straight. It also incorporates a pair of electric screwdrivers, which serve to wind the machine up and release it again. Teaching Jerry to use it was a cinch. "It took about a half a day," Ngo says.

In January, Ngo uploaded to YouTube a video of Jerry playing with the machine. Since then, it has been viewed more than 1.6 million times. Commenters have left remarks like "Simply awesome," and "OMG Best video on YouTube."

One part of the video shows Jerry tugging at a red cord on the machine. Ngo explains that the dog learned that he could force the launcher to load faster. Sadly, the dog can't use the machine anymore. Jerry is 17 now and can barely hear or see. "He had his time," Ngo says.

Jerry needs no help playing with his ball.