hey guys, I was thinking about doing a styrofoam background for my 100 gallon tank. Ive done some research so far and im pretty sure what I want to do. I would be building one to look like slate and being 2-4 inches deep. Tank is 5 feet by 20" Ive been having a hard time finding foam to fit this size, any suggestions on where you all have been able to find foam that is easy to work with that would come close to these dimensions or would i have to piece together something, which I would do if necessary.