Murray,
There are different kinds of rivets- there are 'pop' rivets that use a gun type tool and there are hammered rivets. It is almost assured that a folding camera did not have pop rivets. As far as the hammered type there are rivets which you place through a hole and peen the rivet to upset the dia. and clamp the materials (sandwiched) together.
There are also rivets that you hammer into a blind hole that have sort of a twisted shank. You need to describe the mechanical connection you are trying to repair and I can guide you through it. Including where to buy.
BTW did you ever run any film through that Argus Matchmatic I sold you? Just curious.
Good luck - Matt