I could be wrong but that looks like polystyrene or pvc bord. If its polystyrene I think it is a very easy, smart ,affordable and lightest weight idea. I am going to build a few with Polystyrene. Im sure you will be weighing it down or spiking it for some storms if its poly but I think they may need a one spike In the center or another sheet so it doesn't flex in a high wind situation.