Within the first session of my new box, my PVC piping cracked and broke off. Pissed at this pitiful display of durability, I've decided to shell out for some HDPE. I know it's super expensive, which is why I want to make one sheet go the distance. How much would I need for a box that's 14" wide and 8' long? And how thick should it be? Ideally, I'd like to spend under $100 CAD because thats as much me and my friends can push for.