Dear John-
Sorry I picked up on this late. I thought you would like to see this:
http://www.shipshewanaharness.com/ecommerce/search_results.cfm?search_terms=rivets
I remember using some of these as a teenager when I worked a a canoe camp in Maine. We kept them around to make sheaths for axes out of leather or fire hose.
Marty Pickands
New York State Museum