Was wondering if, could you achieve OPs "paper bitcoins" idea by simply printing a bitcoin paper wallet?

If I make a paper wallet and send 1BTC to it, the public address can be checked to ensure it still contains the 1BTC.

I can give it to Fred as kind of an "off-chain" transaction (say to pay for groceries)

Fred gives it to Sally - again "off-chain".

Sally decides to "deposit" it by breaking the wallet seal, and using the private key to send the 1BTC to her online eg coinbase account.

From blockchain perspective, I sent 1BTC to Sally.

Only flaw here is that, as the original issuer, I also know the private key. Nothing (technically, not morally) to stop me emptying the wallet immediately after I give it to Fred and he originally verifies it.

One advantage of the paper bitcoin is instant confirmation. But requiring trust in the original issuer to not empty the wallet probably makes this infeasible as a currency. Not going to propose a government-guaranteed, 'trusted' central printer of bitcoin currency in this forum! :-)