If I had an SS4, I would gladly whip up some Kydex for you but... I just picked up the Spec-Ops Combat Master sheath in the short version and it fits a ton of medium fixed blades I have. It's a quality piece of nylon and gauranteed for life. I paid about $40 shipped, well worth it especially since I can use it for so many different blades.
Good luck with whatever you do.