🎥 Full build video on YouTube:
👉 LINK
(Complete build process, wiring, firmware flashing, and final result)

This is a budget-friendly, fully wireless split ergonomic keyboard based on the Corne (Helidox) layout, designed to be built without any custom PCB.
Everything is handwired, using easily available parts and 3D-printed case files, keeping the total cost around $25 USD.

The project uses dual Pro Micro–compatible nRF52840 controllers running ZMK firmware, enabling reliable Bluetooth connectivity between halves and to your computer. One half acts as the main Bluetooth device, while the other pairs wirelessly in the background.

Key goals of the project

• Make wireless split keyboards accessible and affordable

• Avoid expensive custom PCBs

• Allow full customization of wiring, firmware, and layout

• Serve as a learning project for keyboard firmware, handwiring, and ergonomics

Features

• Wireless split design (Bluetooth)

• Corne / Helidox ergonomic layout

• Fully handwired matrix with diodes

• ZMK firmware support

• Battery powered with physical power switch

• Low-profile and portable

• 1+ month estimated battery life (usage-dependent)

What’s included here

• STL files for the left case, right case, and plate

• STEP files for further modification

• Designed to fit:

  • Pro Micro–style nRF52840 boards

  • Small Li-ion batteries

  • Standard low-profile mechanical switches

What’s on GitHub / Instructables

Github LINK

Instructables LINK

• Full build guide (step-by-step)

• Wiring diagrams and pin mappings

• ZMK firmware files (ready to flash)

• Keymap configuration

• BOM with direct links

• Known issues and tuning notes

This build is ideal if you:

• Want a cheap wireless split keyboard

• Enjoy hands-on soldering

• Want to learn ZMK and custom keymaps

• Prefer repairable and modifiable hardware

If you’re into DIY electronics and mechanical keyboards, this is a very rewarding project to build and daily-drive.