I first used K&B polyester resin, then Sig. Now I go to Walmart and by the Bondo brand for a lot less and it works just like the other brands. My guess is it is the same product in different labeled cans.
After you use the water based polyurathane to attach the glass to the wood, I normally either use a coat of Zap finishing resin or a automotive quick filling primer to fill the weave. then paint as usual. I used automotive base/clear on my corsair right over the polyurathane. I did use a sealer/primer between the filler primer and base coat.