Electron Dust built the Hexa-Bouncer to keep a ping-pong ball bouncing on a moving platform. Two cameras track the ball while six arms move and tilt a triangular platform to meet its predicted landing point.

According to the creator, the machine uses a Teensy 4.0, six geared NEMA 23 stepper motors, six motor drivers, a 36 V 14 A power supply, two cameras and a GPU-equipped Windows PC. The image-recognition and motor-control software are custom-built, and the many aluminum parts were machined on a desktop CNC.

XA10C4's Ruler Drive turns the familiar trick of twanging a ruler over the edge of a desk into a four-voice automated instrument. Stepper motors change each ruler's effective length to set its pitch, while solenoids strike the rulers; the machine is controlled over MIDI and the published demo performs the notoriously fast piece Rush E.

Built from an aluminum frame and 3D-printed parts, it mechanizes a very simple school-desk noisemaker into a programmable musical robot.