Severin Meyer's Chrumm Is a Slick Raspberry Pi Pico-Powered Open-Hardware Mechanical Keyboard

Developer Severin Meyer has designed an impressively slick open-hardware ergonomic ortholinear mechanical keyboard, based around a 3D-printed chassis and a flexible sectioned PCB — and powered by a Raspberry Pi Pico microcontroller board.

"Chrumm is an open-hardware ergonomic keyboard, made of a 3D-printable body, a bendable PCB, and custom firmware for the Raspberry Pi Pico," Meyer explains of the device. "Chrumm features a column staggered layout with simple thumb clusters. The right side has an additional column, to better approximate the standard ANSI layout, and to provide dedicated arrow keys. A central encoder allows for rotational input."

That's already an impressive list of features, but Meyer's project has more behind it. The 3D-printed shell assembles into a single block with no visible screws, 3D printed using STL files generated from a Python package. "Most parts are printed sideways," Meyer explains, "to produce a smooth surface without the need of post-processing. Custom supports minimize the print time and filament cost."

Inside the housing are a pair of PCBs designed to host the keyboard's switches, split into sections linked by flexible bridges in order to allow the PCBs to conform to the curved shape of the case. A small companion PCB houses the rotary encoder, used to quickly adjust volume, while one of the two main PCBs plays host to a Raspberry Pi Pico as the keyboard's controller.

Even then, that's not the full extent of the project: to finish the keyboard, Meyer designed a matching wrist-rest which extends out at either side of the keyboard's angled front — then finished it in synthetic leather to provide a softer, more cushioned feel.

Meyer has released the source code and design files for the Chrumm on GitHub under the CERN Open Hardware License Version 2 — Weakly Reciprocal; "I share these files in the hope that they are useful," the maker writes, "or at least interesting to others."