If you live in a major city, you’ve probably seen a street performer with some variety of slapophone. It’s a simple musical instrument that typically uses different lengths of PVC pipe to act as resonant cavities. When struck with an implement like a flip-flop, they release a dull but pleasant tone. [Ivan Miranda] decided to build such an instrument himself and went even further by giving it MIDI capability. Check it out in the video below.

[Ivan’s] design uses a simple trick to provide a wide range of notes without needing a lot of individual pipes. He built four telescoping pipe assemblies, each of which can change length with the aid of a stepper motor and a toothed belt drive. Lengthening the cavity produces a lower note, while shortening it produces a higher note. The four pipe assemblies are electronically controlled to produce notes sent from a MIDI keyboard, all under the command of an Arduino. The pipes are struck by specially constructed paddles made of yoga mats, again controlled by large stepper motors.

The final result is large, power-hungry, and vaguely playable. It’s a little unconventional, though, because moving the pipes takes time. Thus, keypresses on a MIDI keyboard set the pipes to a given note, but don’t actually play it. The slapping of the pipe is then triggered with a drum pad.

We love weird instruments around these parts.