I don't think that putting the password inside the envelope is a good idea.
It would be better if you mail it to the buyer or something.
It would be better if you mail it to the buyer or something.
This is just a fun project. You are right not to place it inside envelope, but then again why would I use a wallet like this or send one like this when it can be done electronically? Its just the concept of a physical bitcoin being postally exposed, cancelled, sent and used. If you were a philatelist you would see it from a different angle.