It's very hit-or-miss, but some translucent beverage bottle caps fit just right on some flashlight bezels. F'rinstance, I found a smallish one off a 12 or 16 oz. Poland Spring water bottle that fits like a glove on my JETBeam RRT-1, and a larger gallon jug cap that fits like a dream on my Thrunite Scorpion v2. I also found another one, brand/size unknown, that fits on some of my ~22mm-bezel lights like the AKOray K-106; damn I wish I knew where I got that cap!