I was in the hardware store insulation section today, pricing batts for my walls when I saw some styrofoam panels, of various thickness, and I wondered if they could be used in a manner similar to, if not as effectively as, rigid fibreglass as bass traps? If so, then what thickness would be best? If not, why not? I understand already that it wouldn't be AS effective as the famous Corning 700 series stuff, but it's hard to find in small quantities and I'm also curious about how styrofoam would work in general. Related to that, I also saw some pieces of material used in attic vents (best I can describe as I don't know what they're called. They're shaped somewhat like Auralex's Versatiles, though much longer and thinner. I wondered if stacking several of them together (glued) might make an effective diffusor or absorber of higher frequencies. Again, I know it wouldn't be as effective as other stuff, but it is inexpensive and I'm curious.