When I make a Kydex sheath, it is for an individual knife. I will put a layer or two of masking tape on it, depending on how tight I want it to fit, before I form the Kydex. Kydex will scratch some but part of the scratching problem may be dirt or dust between the knife and Kydex. If you are worried about ruining the sheath, Kydex can be formed many times as long as you don't overheat it. If you just need to change part of the sheath, only heat that part that needs changing because you can do it. When it turns out right, you will be the owner of a custom modified Kydex sheath. Hope this has helped you some. Have faith and God Bless You. Ray Kirk