I ended up using Roxul to make five 24" x 48" panels. I mounted two behind my monitors, one overhead and two to
soak up some early reflections on sidewalls. I've been happy with the results. I chose the Roxul purely on price and
availability in my area. I think Corning 703 would have worked well too but I couldn't find a convenient supplier. The Roxul was easy to work with, very little mess and easy cleanup. I did all the work in the garage and sealed the sheets in wood and fabric. I've had them is use for several years.
Image by
tagruvto, on Flickr