Hi Lemmy,
I'm Martin and have been working on a free and open-source, fully DIY crypto hardware wallet for a couple of months now. I' ve just published the first functional preview of the firmware, which can be built by anyone easily using Arduino IDE, and flashed to a variety of $5-off-the-shelve ESP32 boards from Aliexpress.
The first release will allow for storing up to 30 encrypted seed phrases, and Ethereum signing via Bluetooth Low Energy. Under the hood, it's powered by the cryptographic libraries written and used by Trezor.io.
Support for more interfaces and chains can be added fairly easily due to a modular structure, and there is a whole roadmap planned to extend functionality (starting with support for displays).
If you're interested to learn more, check out the README in the Colibri repository.
Please let me know what you think, and leave a 🌟 on Github if you like the project.
Also if there's anything that you've always missed in or been annoyed by a hardware wallet, your input would be greatly appreciated!