DYI minimalist sandals tip?

Hi all.

I'm in the middle of making my first DYI barefoot sandals. Sole choice is done, but about the straps, I'm torn. Undecided on form factor, material, size... everything.

So I'm asking those who already completed such a project: what did you use, and why?

Paracord or webbing? Round or square section? Nylon, polyester, leather, hemp? Is a 4 mm diameter enough or should I go for 5, 6, more?

My main concern is comfort, then robustness. Elegance, not so much.

Also, I have a sensitive spot just above my ankle. I plan to tie my sandals in a way that the straps won't bother it but, just in case they moved and touched it, what might be the most "forgiving"?

Thanks!