People conduct electric charges, and so do vegetables. This simple fact spurred designer Scott Garner to build the Beet Box: a machine that plays drum-kit sounds at the tap of a beet. The beets conduct body capacitance, or the electrical energy stored inside humans, to a sensor plugged into a Raspberry Pi mini-computer ("Pi" for short). Each touch triggers software to produce one of six percussion sounds. Garner hid the electronics inside a wooden enclosure with a lid so that striking the beets emits clashes and snares as if by magic.
1. Box. To house a Pi, a capacitive sensor, a power supply, and cables, make an 8-inch-square wooden box. Nail together two 4-inch-tall sides, two 12-inchtall sides, and an 8-inch square bottom using half-inch-thick wood. Drill a circle of small holes into the lid for a sound port (but don't nail it on). To the 12-inch-tall sides, add an 8-inch-square plank that's bored to fit six beets.
3. Beets. Solder six wires to individual electrode ports on an MPR121 capacitive touch sensor breakout board. Stick each wire into a different beet.
4. Wiring. Use a wire to connect the SDA port of the breakout board to pin 3 on the computer, and the SCL port to pin 5. Link the board and the Pi's grounds. Connect the board's 3.3V line to pin 1 and its IRQ line to pin 7 of the Pi.
5. Speakers. Hook up small speakers to Pi's audio port. Fit the board, Pi, and speakers inside the enclosure. Run a power cord to the Pi, drop the beets into their holes, then drop some beats.