are we assuming they are not monitoring your internet and credit card activity? If we assume they are not doing that they can bust you when you use it or while transporting it, like they do any other person who is possessing a gun they are not allowed. If you leave it at home in a drawer, and don't commit any other crimes that cause your house to be raided, then you should be fine. If you have a clean record and you can legally own a gun then you can legally make any gun you are allowed to own. It would be very illegal to try to sell it without a manufacturers permit.