I don't think we have a pep version of the sheath. LeeKeegan's build of the knife has a sheath, but he built it out of wood directly from blueprints, and not from pep.
just use reference pics for the sheath and make it out of card board or wood (or metal if you can). there's a pep file for his knife in the official reach file index in the noob forum. i was planning on a ghurka kukri and creating the custom sheath for it. possibly the best and coolest looking knife/machete ever. the bottom one is emile's style