How do you rivet a hard hat to a paper mache dome??

I prefer bolts and nuts to rivets because they're easier to take apart later. For some reason, in the country where I live, the hardware mongers use the expression, "machine screws", to refer to tiny sized bolts.

As far as I can tell, the only difference between bolts and machine screws, is size.

Pop rivets ? Then use backing washers to spread the pressure over more the hat and papier mache

+1 The clue was in your use of the word Rivet!

Or just use hot glue