Are you looking for a way to attach your keychain to a piece of aluminum, ...why not just drill and tap the receiver piece itself?
The keychain is just an inspiration. Basically, I'm trying to find an easy way to make a sign-board where I can quickly swap out parts of the message by removing and re-hanging, but I need it to be wind-resistant, and I'd like it to be cheap. I was going to just use a small clevis pin and a small cotter pin,
but there's a slight bit of torque on the clevis in that setup, and it would work better if the pin was square to the aluminum sheet... so my choices were either epoxy or find something screw mounted.
Truth be told, a chicago screw might work better, but it's slower to take apart.
.why not just drill and tap the receiver piece itself?
I once made a cut with a circular saw that was un-true in all 3 axis. Mechanical hardware and I don't get along.