Various materials are used including the dyed string and commercially available cotton floss.
The string has a more substantial thickness so the areas populated with string weaving have a characteristic thickness. The floss is very thin and even though it was double-doubled (four strands) it doesn't cover nearly as much as the thicker cotton string.
The buttons are a poly clay that was formed and printed with a walnut shell to achieve the texture (sorry you can't see it here) then overcooked to get the natural dark brown color. This extended cooking also assures that the plastic is fully fused together.
heather and blue grey one button strigweave cuff
heather grey one button cuff
more string weave bracelets
More of these are available for you to purchase in the ETSY shop in the tapestry cuffs section