Daniel Bauen made a nifty pedal-powered tennis ball launcher

Both cleanly powered and built from 2 recycled bicycles, scrap steel and wood, leaking 5 gallon water jug and a lacross stick, our pedal powered tennis ball launcher was created as a unique entry for the Innovate or Die pedal powered machine contest.

It allows players varying in skill levels to practice to be better at both tennis and cycling. The launcher is towed to the court on its built-in bicycle trailer. A bike is secured to it and functions to drive the device. Pedaling the cycle as one would on a trainer drives the two launcher wheels. The cyclist then aims and pulls the lever to launch balls to the hitter.