Well, if you ARE sealing them you shouldn't have a problem with evaporation. I mean you have rubbing alcohol in a container with a screw on lid for what, ten years? More?
Without it evaporating, I mean? Open the lid and it will be gone in a few days!
I would avoid food products though as, if it does leak, you may be attracting pests...
There are some great resins, but I was thinking you wanted it to flow inside a clear container to look like it was fluid filled. What do folks use inside their TOS Hypospray ampules? (Or heck TNG ones too, for that matter!)