This cute hand-built quadcopter might not be able to play tennis, but it's not CrazyFlie's fault — it's much to small to bounce anything around. The copter is basically a flying printed circuit board and not much else.
The whole thing weighs just over an ounce and measures about 4 inches on each side, yet includes a 3-axis accelerometer, two gyroscopes, a charging port and a tiny model airplane battery that gives it four and a half minutes of flying time. The battery and propellers are from a Silverlit X-Twin remote-controlled airplane.
The 64-mHz CPU uses data from the accelerometer and gyroscopes to make tiny adjustments 250 times per second, keeping the tiny copter airborne. It sounds somewhat like a bee swarm, or like an elegy on Autotune. Watch it in action below.