I've been working on making my own hurache/tarahumara running sandals for sometime now.
Seeing some other examples, I've been working on these off and on for close to 2 years. I've tried a variety of materials, and tying methods.
I think I've come up with what works best for me.
So with my penchant for bikes, I found what works best is a relatively smooth BMX street tire due to it's width and lack of knobs. Some traction is good otherwise they can get "slippery when wet."
I first used 1/4" leather cord. These held together, but cut into the skin, which was rather uncomfortable. I switched over to a old pair of shoelaces I had, and these were a marked improvement. When these wore out, I found some 1/2 inch thick shoelaces. Best fit and usability thus far.
Now tying them was the biggest ongoing process. I have figured out how to tie them so that I can simply slip them on and off with having to retie them each time, and they still fit snugly enough for running.
A work in progress, but now a working solution.
Plus they make great Christmas gifts!