At one job I was afraid of losing a set of keys, so as an extra backup, we had a physical copy of the the key printed out as a QR code. This was then physically

At one job I was afraid of losing a set of keys, so as an extra backup, we had a physical copy of the the key printed out as a QR code. This was then physically locked away (safe deposit or similar). But I like this as an option for a “failure resistant” offline backup. The main benefit is that doesn’t assume a stored away USB stick will still be readable while still having a somewhat machine readable format. Yes, the QR code was very large, but could be split into multiple files if needed.