So, I have these fiberglass tower speakers I made, and I noticed that my low chamber isn't particularly well sealed off from my high chamber. I tried using fiberglass resin to seal off the chambers, but this is proving to be very difficult to work with in this application and is fairly expensive. My next thought is to use plaster to help seal off this inner wall. It doesn't have to be structural, since all of the structural ability come from the fiberglass shell, it just has to stop the low tones from distorting my highs. Does anyone know the acoustic properties of plaster? Or any other cheap easy filler type material?