I've been carrying one of my knives every day for a while. I had to make a sheath for it a while back because its original sheath was to loose. Now the sheath that I just made is loose again, enough that the knife will almost fall out if held upside down. The sheath was nice and tight when I made it. This is a waterformed foldover sheath made with good quality 8/10 oz. veg tan leather. I can send pics if needed. My questions are, how do I make sheaths that don't loosen up over time, and why are they loosening up? Maybe I have been waterforming wrong? Any help appreciated.