Growing up the only material I thought slings were made of was leather. In a pinch I would use my boot laces and cut out the tongue of my boot for a pouch but by and large, they were all leather or mostly leather.
Skipping ahead well now I know slings are made from many different kinds of material, wool, plant fiber, animal hair, leather, etc. In my search for the perfect combination or type of sling, besides the Chamorro sling my personal everyday favorite sling is a combination of leather and jute.
This is how it's done. My work and cutting pad has a one inch by one inch grid to show the size of materials and components.