Generally speaking, there’s no such thing as federal “registration”. The only exceptions that I can think of are NFA items: suppressors, short-barreled rifles

Generally speaking, there’s no such thing as federal “registration”. The only exceptions that I can think of are NFA items: suppressors, short-barreled rifles and shotguns, etc. You could stamp a serial number on a piece of pipe and register it as a suppressor with a Form 1 - but that would cost you $200 and require that you file a Form 20 every time you travel interstate with it, so that’s not really a reasonable option for this.