There are some pop rivets which are threaded on the inside and claim to be usable like installing a nut into a piece of sheet metal. They clain, you can then install a machine screw in the rivet and remove it again.
don't believe em, the rivets will loosen up in the original sheet and turn with the screw, thus being non-removable and never tight. sure could be handy if that process worked but I've seen lots that didn't. Tom
