hole in gas tank

So as the topic reads I was riding Saturday and a stick came through my drain hole in the skid plate and put a gash in the tank. Its about 1/2" wide and 3"s long. I was wondering if any of you guys knew how to repair a plastic tank and what works best. Anew tank is around 500 or so dollars and I would rather try to fix this than spend the extra change. Thanks.