I just cut as large a circle as possible from a rawhide scrap, then using a sharp knife, stuck into a stable log, cut slowly, about max1/4inch strip round and round untill you get to the centre. A bit like you are using a sewing machine. If you can cut thinner that's OK, but needs practice. Rawhide needs to be plyable, so damp and flexible, but not soaked, if you get the idea. No need to further process, can be used as thronging, or to tie arrowheads, etc. Many uses.mind yer fingers!
Can be done with sharp scissors too, but its never as neat.