All of the bifold and trifold wallets are made from kangaroo leather and entirely hand stitched.  They are expensive ($140 for a bifold or trifold), but they last a long time and are all unique.  Kangaroo leather is extremely strong and supple for its light weight, making it ideal for things like wallets and braided goods.  The kangaroo leather comes from sustainably managed ranches in Australia.  The simple card holders are from Hermann Oak cow hide.