Wonderful! Thank you so much for the informative post!! That's very awesome of you.
I don't know how much bb pellets are...but for rivets on some small pieces I've made, I've snipped the round tops off of those duo tang bendy things. A bit flatter and rivet-y plus, you get a whole carton for a buck!
( actually, I've snipped the tops for nailhead type studs on clothing pieces...for the foam I actually poked them through and bent the prongs to assist in holding the elastic in place...functional AND stylish! haha )