Get them from eBay:
https://stores.ebay.co.uk/Silver-Coasts/Sewing-Leather-Craft-Tools-/_i.html?_fsub=3104412013&_sid=853213773&_trksid=p4634.c0.m322
these rivets can be used on leather, or fabric, they are nickel free, and non rust.
The Strong-Drive SDWC Truss screw provides a stud-to-bottom plate or stud-to-top plate connection as well as fastening trusses and rafters to top plates. The full-threaded shank engages the entire length of the fastener, providing a secure connection. The Strong-Drive SDWC Truss screw is the perfect fastener for constructing a continuous load path and the orange top coat makes inspections quicker and easier.