Thanks guys!
Eyelets and the tool. Gotta get the eyelet tool (and a small jewelery hammer... easier to work with than a regular sized when doing fine work)! https://www.volcanoarts.com/cart/eyelets/
The buckles I made myself using floral wire. The circles are jewelery jump-rings from Michael's Crafts. (bead landing brand)
Thank you for the tips. Much appreciated.