The way I do it on my neck knives is this. Take the pipe you are using, I believe 1" is what I use the most. It might be 1.5" thought. next cut a 2" slit down the pipe. this allows it to flex without bolts or rivets. Next heat up the pipe till pliable with a heat gun or propane torch. Then flatten the pipe between a couple boards, books or something. Be sure your slit is on one of the edges, not on the side of the pipe. now simply reheat the pipe, and stick the knife as far in as you want it. let cool and you are done. If it is too tight, grind a little off the opening to the sheath, It will loosen it. then just drill your holes for attachment.