Depending on the thickness, (less than 2mm, forget it ) & the way it was tanned ( chrome tanned, forget it ) You could dip it in hot bee's wax or plunch it in boiling water ( the roman centurion's breast plates were made from boiled, moulded leather)..............if it's like a floppy suede then there ain't much you can do about it, maybe use several layers in thickness or make a pouch in a stiffer material then cover it with your leather........there's nothing wrong with soft pouches but if you really want a firmer one then prehaps investing in some veg tanned might be a better option.