Ah yes, rivets. Three kinds on an Airstream: buck rivets, POP rivets, and often, Olympic rivets.
Most, if not all of the rivets on the outside are buck rivets. They are the type that takes two people to put in. One with the rivet gun on the outside, and another on the inside with a block that makes the rivet spread to hold itself in. Since they are solid, there is less chance that water can come in. Seams are sealed to further protect against water infiltration.
But when the buck rivets pop out, unless you are willing to remove the inner skin behind the rivet, you need to use another kind, the Olympic rivet. Read up on them, they are quite useful for doing repairs on the external panels.
The POP rivets are what is used on most of the inside, and are the ones you can buy a simple tool to insert them with.
Many people feel that one of the signs of bad axles is missing rivets, or finding them on the floor inside the trailer. The idea being that a bad axle shakes the body much harder.
♫ My mommy said not to put beans in my ears ♫