I just put some in a SS bezel from PEU. I was going to use a clear, two-part epoxy but then I found a UV curing glass adhesive at Home Depot. Made by Superglue and on a black and red card. That stuff worked great, but it was thin and runny. Have to have the trit in a slot for that stuff. Being thin was actually a plus for me. I put a drop on a piece of glossy paper and then used a toothpick to put in small amounts. Just touched the toothpick to the side of the slot and it would capillary action in, leaving no bubbles and self leveling out to a clean smooth surface. Hit it with the UV LED light and voila! Having it smooth and level to the surface means it won't clog with lint and be easy to clean.
I guess you could surface mount the trit. I'd use a two-part clear epoxy. Thing is it would try to run flat before it would cure, so you might have to let it start to stiffen before putting it on the light. I would think you would want to have a "bubble" of clear epoxy with the trit in it for protection. Another idea would be to find something with a negative bubble shape for a mold (cutting the tip off a sharpie pen cap for example), wipe inside with car wax so it will release, and then pouring in a little epoxy and putting the trit in it. After it cures you would have a hardened bubble that you could then epoxy on the flashlight. Smaller and closest to the size of the trit vial would be best for light transmission. Also, the quick set epoxies are usually not good in moisture, i.e., sweaty pocket - they tend to get a little gummy and soften some. Use the long curing stuff.
