You can thin it with denatured alcohol up to about 30%. Make sure you get the purest you can, ask the drugest and he should have some 99% pure behind the counter.

If you want any strength from the Poxy then you should put on a lite glass cloth under it, 1/2 or 3/4 oz is all you need. Pour it on and the use a scraper or old playing card to spread it around and work it into the cloth. It doesn't take allot to seal the cloth to the wood and the cloth adds allot of strength without very much weight.

Let it dry and add another coat then sand it smooth with 600 weight wet&dry - dry of course. You can give it a lite spray of grey prime to show any low spots or imperfections during sanding, just fill them or seal the cloth with a bit more Poxy and re-sand.