The primary risk with this is that someone steals one of your backups and manages to discover or brute force your password (which is why a strong password is necessary). A secondary risk with this setup is if all your backups are lost, stolen, or damaged in the time between when you verify them and you lose access to your primary wallet, your bitcoin will be lost.
Required:
- The items required for Paper Data Record.
- Multiple fire-proof, water proof, light-proof, tamper-evident, and locked storage (~$30 each)
Variable Parameters:
- Seed
- Type of safe
- Storage locations
- Frequency of backup verification
- Write your full seed on at least 2 pieces of paper, using the instructions at Paper Data Storage.
- Store seed in different locations (eg at home in a fire proof safe and in a safety deposit box). If your seed is passphrase protected (which it should be), there's no particular need for this to be behind an additional lock since if you lose it or its stolen, you have at least one additional backup. You can even give this to a responsible friend.
- Verify that all backups are still in your possession regularly (eg once a year).
- Paper is not durable, so the durability of the backups are dependent on the safe protecting the paper from wear. Leaks in the safe, insufficient heat insulation, or accidentally leaving the safe open could cause your backup to be irreparably damaged.