Very cool project! Would make a great bitcoiner Christmas present!
“Nostr Key Backups
The machine is general purpose enough to engrave anything within the physical constraints of the plate. Backing up your Nostr private keys (NSEC) on steel with scannable QR representations allows a stateless device such as a SeedSigner to securely sign Nostr events.” nostr:note1pgml9jw5rmpsnjn8u3kxnxhdaf3rwky8p4hnn052stffzphrra7qurueg3