Thats exactly what I did for my boning knife. A grinder to shape the pipe, propane torch and about 12” of pvc pipe. I think I used 3/4“ pipe if memory serves. I also made a sheath out of an ABS pipe, a piece of plastic electrical conduit, and even a piece of pex pipe just to see if it would work. Took about 10 minutes to make the sheaths and then I sprayed them neon or bright red so I don’t lose them if I set them down. They work great and don’t come any cheaper!Should be able to easily make one if you heat up some thin PVC pipe or kydex, especially if it is not to belt carry, but simply protect you blade/pack while stored in your pack.