Colibri is a free and open source DIY project, with the goal to enable everyone with $5 and access to a laptop and Internet™ to create their own secure crypto hardware wallet, using off-the-shelf ESP32 hardware development boards.
Head over to colibri.diy to find build instructions and more information!
Just released v0.0.3 of colibri.diy - new features include Ethereum transaction signing and basic Bitcoin support <3
Now working on a companion webapp to ease device setup, and the first 3rd-party wallet integration. Please let me know what you think!
Regarding encryption, I'm gonna write up a security-doc that goes into more detail, but in a nutshell yes, keys are encrypted using your password (see also here in the build instructions). Your password is salted and hashed and turned into a 256bit key. The ESP32 has a hardware AES module on board, and encrypts your crypto keys with AES-256 CFB128 before storing them. The password itself is not stored on the device. Currently you'd need to send the pw via RPC command to unlock the wallet, in the future you'll be able to input it on the device directly (display- and GUI-integrations are planned for 0.2.x).
After setting a pw, you can either add your existing keys, or generate new ones on-device (ESP32 comes with hardware TRNG capabilities). In the latter case, they're returned to you once in the RPC response so you can back them up, in the future you'll be able to show them on the display instead.