Surprisingly, there are precious few who still glass models in our club and our membership is top heavy with senior citizens. It seems everyone was seduced by the simplicity of plastic iron-ons. As a matter of fact, I'm going to do a demo at our next meeting just to show some of the guys that never glassed before that it isn't all that intimidating to do. Don't get me wrong, a lot still apply glass tape for reinforcing the wing joints but thats about it.
I've tried all three methods and to be honest, I find the polyester resin to be the hardest, toughest finish of all. Second is epoxy and if you just want a soft yet relatively durable surface, then use the polycrylic method.
I need to remind you that with the last method, you're bonding the glass with a clear paint and not a true resin. I've mentioned in posts in the past that I had my reservations regarding this method since there is no true chemical bonding as in the epoxy and polyester methods. You see the fiberglass manufacturers coat the glass cloth with one of several types of finishes that form a chemical bond between the glass fibers and the resin. So the resin sticks not only to the balsa wood but also to the glass so you get a coating that is bonded to the wood and not just lightly stuck to it. You definitely need to allow the polycrylic to dry completely. It too will be fairly tough. I suspect that moisture was the culprit for the bubbling too.
Don't get me wrong, you can mess up applying with epoxy too. Such as thinking you can thin it enough with denatured alcohol or acetone and not affect the bonding qualities. You should use a finishing resin.
And as for polyester resin, I stay away from the stuff you find at auto stores even though I'm sure many people use it and are happy with it. I tend to find it a bit too thick to flow out and many times, it remains a bit too tacky since it is in reality a laminating resin meant to apply several layers of glass cloth and you want the tackiness when applying the next coat. The type I use is a thin resin with wax added to facilitate sanding when done. If you need to thin polyester, you would add styrene monomer to the mix. There is a wealth of knowledge that can be gathered if you select the right websites.
The info on the glass cloth I got from Thayercraft ...
http://www.thayercraft.com
The info on polyester and for supplies I go to U.S. Composites ...
http://www.uscomposites.com and also AeroMarine Products at ...
http://www.jgreer.com
Hope this helps.