Firefly Hardware Wallet
The Firefly Hardware Wallet is a low-cost (under $5) DIY Ethereum Hardware Wallet, which is securely air-gapped and mobile friendly.
The problems this project addresses are accessibility, affordability, safety, recoverability and user-experience regarding the secure management of cryptographic private keys.
Part of security is the on-chain multi-sig wallet (requiring no transaction fee to use) which enables a safe 2-of-3 multi-factor wallet, along with password recovery and hardware failure recovery. Up to two factors can fail with a cost-of-capital, time-lock release and signalling rewards help prevent large-loss by rewarding single-factor leaks.
All source code, hardware design and 3D-printable models are open-source, released under the BSD license.
Using the Firefly Hardware Wallet
Logging Into and Sending Cryptokitties Transactions
Cthylla Authenticated BLE Beacon
The PCB and hardware design used for the Firefly can also be used in the Cthylla Authenticated BLE beacon, which which was a project we built for a more recent hackathon (ETHDenver).
Cthylla allows ERC-721 tokens to be generated entirely off-chain and offline, fully redeemable on the Ethereum blockchain.
Since uses the same hardware design and PCB (less the screen), the design is re-usable and may allow lowering the per-unit cost by producing two products at once, and could also be used for other projects.