What about a spray varnish? Or a paint sealer, like the kind used for hobby paint?

Epoxy resin is not made by stained glass supply companies. I use the bar and table top resin from http://www.uscomposites.com/
It is a lot cheaper then what you get from stained glass suply companies.

Barrel, I don't think envirotex is from stainglass companies, although the brand liquid fusion is and yes they price it quite high. Like enviro - famowood is another cheaper alternative.

TF, maybe varathane but I would be concerned about any urethane products... they have been known to yellow in some cases. I can't remember what Silva uses on her frames but I think she's done well with one of these products

Varathane is on my list to consider and I am going to check on the famowood as well.
Thanks guys. This tells me I am going in the right direction.
After seeing a crafter that decorates charger plates and coates them I know these boxes could be done with this.

Texas, I have had luck with the famowood that you can buy at Lowes or home depot. it gives a really tough shine, I used it for my mermaid sink and then again for several of my plaques. Had one disaster but it got corrected with elbow grease. only thing is it is for indoors only but that is what you wanted and it is very very messy..

I also would be worried about the varathane, I used some of it on my first address plaque, and ended it yellowing. I found out later that it is better to use several coats of crystal clear Krylon sealer. It works great for indoors and outdoors.

Good luck

Thanks Linda. I have been a bit under the weather lately off and on and haven't gotten to Home Depot.
I am going to go with the famowood as soon as I can get over there.