Has anyone used this in their vivs? I'm wanting to expand upwards with a couple vivs I've built but it's impossible to find pvc panels around here. I happened to see this at a tile store and it seems like it should work. It's fairly rigid, it's made from extruded polystyrene foam. It's made for tile so it's waterproof. My plan was to use glass on either end and the doors and use this or pvc panels, if I can find them, for the back wall.