I made two or three of the liners before I was satisfied with the one used. Since I drink a lot of milk the cost was minimal. (Rinse the bottle out before use.) An electric hot plate will work while still black, but once it gets red it is too hot. I found I got the best results with a paint remover heat gun. (let me stay in the room where the TV was too.). The bottle plastic is ready to bend and mold when the frosty appearance turns transparent. It'll turn frosty again as it cools (at least the local milk bottle plastic does). Aim the gun where you want the bend. Be quick though as just a little more heat causes holes. Wear gloves unless you like handling hot things. Once the shape is in, hold the edges together then heat them and crimp them together with your gloved fingers as soon as you see them soften and turn clear. Get the final shape and fit with the blade in, but don't get the blade hot. Let it cool if needed. In my experience no part of the operation got the blade hot. Just luke-warm as the plastic is what was heated and that kept the heat. Rather than use glue, I left some small tab points as anchor points around the edge and just sewed them into the leather. Each stitch is a lock stitch with waxed thread, so it should hold together longer than I or the leather will. Two rows of stitching add to the effect. I thought of doing the leather welt thing, but it looked like a lot of extra work that would be less protective than a plastic liner. It is a friction fit, and assuming dryness the knife can stay in the sheath for a very long time without worrying about the leather corroding the blade, which also means how the leather was tanned becomes a non-issue, which aids in leather selection. In experiments with other knives I am leaving a very small drain hole near the bottom so the sheath liner won't retain water when worn in the rain.