This is some Snowden level security.
Shuffle a deck of cards, then play SeedPicker Solitare to turn the deck into a #Bitcoin BIP-39 seed. Put the cards back in the box, tape it shut and toss it in your junk drawer. https://jimbojw.github.io/seed-picker-solitaire/seed-picker-solitaire.pdf
Discussion
Should be an old, beat up deck of cards with obvious wear. OK if it’s missing a few (up to 6 missing).
Put another untapped deck in the junk drawer in case someone wants to actually play cards.
When traveling by air, use an airline branded deck for extra opsec. Use ordinary bicycle cards if traveling by other means.
If discovery is immanent, take the deck out and shuffle it, or drop/scatter the cards to destroy the seed.