This is the second kydex sheath I have made for this thing. I swear I have spent almost three hours tweaking with a kydex, to come up with something that will make a solid "click." I put my oven at 265, and preheat, put the kydex in there for 6 - 8 minutes. I take the kydex out of the oven, I put the knife in between the two layers of kydex, sandwich all of that between two layers of sheath foam, and then I put a piece of 3/4" plywood on top of everything, and I stand on top of the whole enchilada, and I bounce up and down. Oven not hot enough? Need to leave kydex in there longer? Need to press this in a c-clamp or a vise maybe?