Comment by filleokus

Something similar again is my little tool hemlis [0]

It uses Shamir's secret sharing algorithm to generate shares where the private key is split in n shares with k needed to reconstruct it. The bytes are encoded as word on a PDF (either 'burnt in' or written manually with pen to minimise the risk of storing them on printers etc).

That way you can spread the risk of loosing the physical key, while still maintaining some assurance that e.g your friends can run away with the key (or be compelled to hand it over to some threat actor).

[0]: https://github.com/filleokus/hemlis