Andrea sent in this awesome pedal powered tennis ball launcher!
This is a chimera tennis ball cannon made from a bike that you can pedal. It is both cleanly powered and built from recycled bicycles. 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.
Pedal powered tennis ball launcher – Link.