answer:Possible. Go for it. Leather edges may be stitched when they would rub against the skin, when the leather shows a distinctive grain and may tear on the grain or when the finish just looks better than leaving it raw. You could also bind the edges with another piece of leather or a piece of fabric. Or stitch a trim to the leather edge, such as rope or fabric-covered piping. I don’t know about the specialties of cork, but I’d assume that it would have to be treated to withstand any dry conditions, since old, dry cork crumbles upon touch. As for the best material for the insoles and outsoles, that may depend on what feels good to you, what wears best, what you can put your hands on. Leather once did all of it, but cotton or wool flannel linings absorb moisture, and modern technical fabrics for running and biking wick moisture away from the skin, so your choices abound. edit: note how the edges in the picture seem beveled, and the fabric wrap may be linen or canvas. You do have to stitch to keep the buckle in place, so stitching everywhere ties the design together.