A paper wrap envelope item already exists in the game but it's not publicly available to the regular folks.
I suggest that with a piece of paper, you can use the verb envelope, taking as argument any amount of chy on you. You're given an envelope, which can be unwrapped, revealing an amount of chy. Make sure this can be slipped beneath doors, and stored in other places. It basically would have the same size and properties as a letter.
This would be great for dead drops, not limited to wallets with 15K or 10K chy. Hide them in alleyways, slip them under doors, put them in lockers...
