Making your own tools... well that is the height of true craftsmanship.
I've made rivets from wire, to join two pieces of metal - but they were a small gauge compared to those knife rivets. The key is to drill a hole exactly the size of your wire (brass, copper, soft metals). Then it's easy to make a rivet head that'll hold it, with your hammer. Easy as in, practice, practice....
But the heavier gauge for a knife rivet wouldn't be cheap afaik, or maybe not easy to find either.
Scrap metal places can turn up all kinds of stuff, but it's likely to be hard, you'd have to anneal it to make it work...
Can't wait to see the pix how your machete turns out.
That checker work is something, too.