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/