Credit where credit is due, the crypto space has some innovations in this area. Fully analog secret storage has a few options I have come across. One is where you punch/stamp your secret into a piece of steel. The blank is pre-scored with a template or letters so you can do this with just a hammer. The other is where you have little rings pre-stamped with letters/numbers which you then assemble onto a tube.

A random site[0] I found offering some of the solutions. Given the industry, I assume this is just the most highly astro-turfed platform, but there you go.

[0] https://cryptosteel.com/

That's very cool. A lot of work to encode a long ssh key.

The way that works in crypto is that, you generate a private key (such as an SSH or GPG key) from a mnemonic passphrase and punch/engrave those words on a metal plate.

Signing keys like ssh keys aren't so important, you should be able to replace those out of band. Decryption keys are more important to back up.

If I lose my ssh keys the business I work for will no longer have access to their production sites.

They can rebuild them from backups somewhere else but that is about it. They're printed on paper in a safe because of this.