$10MMaybe this could be a way to back up a Bitcoin wallet for the next 50 years:
• 12-word BIP39 mnemonic engraved on a steel plate.
• BIP39 passphrase made from 11 words, generated with dice rolls and stamped onto numbered steel washers.
• Complete receive and change descriptors stored as QR codes.
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Passphrase in lower case separated by a single space, non space before first word and after last