offline cash is cool but I think the old tried and tested method is what's going to work but i understand that it is currently regulated out of existence.

Its where its a basic paper note, redeemable for gold bitcoin on demand. You are obviously trusting the issuer in this case but with this trust comes a reduction in cost but also an increase in durability among other things. Not sure NFC tags can last more than a 10 years- But who knows.