I use two USB drives and a CD-R to store my keys offline as shown in the picture below
Tails 1 - Watch only wallet that creates transactions and broadcasts them, doesnt sign it
Tails 0 - Signs bitcoin transactions offline
CD-R - Stores encrypted gpg.txt file that uses a 22 character phrase obscured by Shamir's Secret Sharing key for 3 out of 5 signatures.
Paper - Share 1 out of 5.
I only sign bitcoin transactions using Tails 0 that will never connect to the internet physically. Tails 1 creates the transaction and broadcasts it with only a split second internet connection. I've made about 4 CD-Rs that are only allowed to be decrypted after you find atleast 3 out of the 5 shares. Tails 0 along with Tails 1 have separate 22 character SHA-256 passphrases that are required to unlock persistent storage on each USB drive. The passwords for those are also scattered elsewhere.
https://www.youtube.com/watch?v=-tLoiLo5fT8
>I'm also destroying the USB drives tonight and replacing them with different ones. Usually these are located in a locked drive bay on an HP z640 that requires a key to unlock the side panel.>>60548104based.