Actually, making your own money is not a new idea. The whole concept of writing a check is based on the idea of making your own money.
Just like any other money, your self-made money (check) must be covered by whatever covers money in the whatever country the check is made.
We even refer to check writing as making money, e.g., when we ask "Who should I make it out to?"
The reason you cannot just scan dollar bills and print your own is not that it is making your own money, but that it preceisely is not making your own money but making someone else's money (e.g., Federal Reserve's).
After all, money is nothing but an agreed upon means of exchange. As long as the money you make (the check you write) can be exchanged for the money someone else makes (e.g., the dollar), or for a comparable value, it is acceptable.
Other examples of money made by someone other than the government or banks could be the American Express Travellers Cheques, bonds, various gift certificates, E-gold, etc.