a 48-key isomorphic MIDI key controller

[BETA] 0x33.board isomorphic MIDI keyboard

Sold by hw.s-ol.nu


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The 0x33.board is a 48-key isomorphic MIDI key controller.

It supports USB-MIDI, TRS-MIDI (out only) and I2C. It also has a jack for 1-bit line output. The 48 keys of the main note surface are arranged in four staggered rows of twelve keys each. Each key has independent RGB backlighting that can be used to highlight scales.

All settings can be changed on the device using a small oled display and three dedicated menu/navigation keys. The firmware is open-source and can be extended in CircuitPython.

beta status

The beta hardware boards are firmware-compatible with and identical to future production boards. The only difference is a layout tolerance error that requires a hand-soldered "bodge wire" to be soldered and taped in place on r4 boards. This isn't visible from the outside and does not affect performance in any way.

  • a fully functional, assembled 0x33.board with an r4 PCB
  • a laser-cut MDF or acrylic case
  • the schematic, board, CAD, and firmware sources (all open source and already available)
  • 1:1 support and access to a user community (if there is interest)
  • continued development of the firmware
  • not included as of yet:
    • a USB-C cable (to power and/or connect to a computer)
    • a TRS-MIDI to MIDI cable (to connect to 5-pin DIN MIDI gear)
    • on-board software synth

isomorphic keyboard layouts

An isomorphic musical keyboard arranges notes in a regular grid in such a way that the distance between keys corresponds to the musical interval between them, which means that musical concepts like scales, chords, intervals or even entire melodies become physical shapes that can be transposed by simply moving them around on the keyboard.

There are multiple different isomorphic keyboard layouts that work on a hexagonal grid. The 0x33.board firmware currently supports the Wicki-Hayden, Jankó, Harmonic Table and Gerhard layouts, but others can easily be added to the open-source CircuitPython firmware.


  • super compact MIDI keyboard (two or three octaves, depending on layout)
  • 51 custom designed, hexagonal ABS keys using Kailh Choc low-profile switches
  • individual RGB backlighting highlights musical scales
  • USB-C port, ESD protection
  • laser-cut MDF or acrylic case
  • hackable CircuitPython firmware
  • certified open-source design (hardware and firmware)
  • designed and hand-assembled in Italy

Links to code and documentation

Documentation (s-ol.nu)

Code (git.s-ol.nu)

Design Files (git.s-ol.nu)

Certified Open Source Hardware - OSHW IT000010

Product HS Code: 84716060

Shipping policy

Parcels are shipped using UPS International Standard (tracked) shipments. For destinations outside the EU, you may be charged for import tax and duty.

If your country is not listed for shipping, message me via any of the social links and I'll do my best to find a shipping solution that works and add it to the store.

For products that are assembled and customizable, please allow up to two weeks between order and shipping: Depending on stock levels and your choices, I may have to order some components to put together your order.

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the 'lil sibiling

The seller


Milano, MI, Italy
17 orders since Jan 5, 2022
I'm a designer and creative technologist living in Milan, Italy.
I have a background in game development and programming but also like to spend my time with electronics and CNC machining, working on experimental input devices and music equipment. Some of my experiments are for sale here.