Ivan Miranda built his following on absurdly large 3D prints, but his most memorable projects are the ones that actually do something. Here he goes musical, designing and printing a MIDI Slapophone — a slap-to-play instrument that pairs 3D-printed parts with motors, an Arduino, and MIDI so it can be tuned and triggered like an electronic instrument rather than just banged by hand.
What the video covers
A slapophone is a percussion instrument: you slap a paddle against the open end of a pipe, and the length of the air column inside sets the pitch. The traditional version needs a whole rack of fixed-length pipes to cover a range of notes. Miranda’s twist, as documented by Hackaday and TechEBlog, is to make the pipes variable-length: he builds four telescoping PVC assemblies, each driven by a stepper motor and a toothed belt so it can extend or retract. Lengthening the cavity drops the note; shortening it raises it. Separate stepper-driven paddles — layers of yoga-mat material sandwiched in 3D-printed brackets for a clean, springy strike — do the slapping.
The whole rig is wired to an Arduino that listens for MIDI. The 3D printer earns its keep here as the fabrication tool: brackets, adapters, frames, and pulleys are all printed. As usual on Miranda’s channel, the fun is watching a maker problem-solve in real time, with the missteps left in rather than edited out.
The bigger picture
This build is a tidy example of 3D printing as a means rather than an end. The printer isn’t the star — it’s the thing that makes a one-off electromechanical instrument achievable in a home workshop, producing the custom brackets and mounts that would otherwise need a machine shop. Combine that with cheap stepper motors, belts, and a microcontroller, and a hobbyist can build moving, interactive hardware that would have been a serious engineering project a decade ago.
MIDI is what ties it together. It’s a decades-old control standard that lets electronic instruments and controllers talk to each other — notes, timing, and other performance data — independent of how the sound is actually made. That’s why a MIDI keyboard can drive something as unconventional as a rack of motorized pipes: the keyboard sends note data, and the Arduino translates it into motor movements. It’s the same logic that lets MIDI drive synths, drum machines, lighting, or any number of maker-built contraptions.
It also fits Miranda’s track record. He’s best known for genuinely large-scale work — he’s built what he calls one of the world’s largest DIY 3D printers and used it to print a life-size model of himself, among other oversized projects covered by outlets like Hackster.io and Tom’s Hardware. The Slapophone is the same maker instinct pointed at something small and interactive instead of merely big.
What to watch for
- The clever-but-awkward trade-off: because the pipes physically move to change pitch, retuning takes time. Per Hackaday, a MIDI keypress sets a pipe to a note rather than instantly sounding it — a real constraint worth understanding before you imagine fast melodic runs.
- How the printed parts hold up under repeated mechanical impact — paddle brackets and motor mounts take real abuse on a slap instrument.
- The MIDI-to-motor logic on the Arduino, which is the transferable idea here: the same approach drives all sorts of physical, MIDI-controlled maker builds.
More from Ivan Miranda
For Ivan at his big-build best, check out “I 3D Printed a GoKart to fly around the world” — a far more ambitious, ride-it-yourself project that shows the other end of his range.
Credit: All footage by Ivan Miranda — we summarize and embed creators’ work to point you to the original. Construction details above are drawn from third-party coverage of the build (Hackaday, TechEBlog). Watch the full video and subscribe on Ivan Miranda’s YouTube channel.
