Well, if you don't make the bill unfit to be reissued (or don't intend to), you're in the clear in the US. The law with coins is more lenient; as long as you ar

Well, if you don't make the bill unfit to be reissued (or don't intend to), you're in the clear in the US. The law with coins is more lenient; as long as you aren't defacing them fraudulently, it's not illegal.