Home made absorption panels.....

Cut 3/8" foam core art board to any size you like. Cover the foam core art board with one or two layers of light Dacron batting used for quilting. Use spray craft adhesive to hold the Dacron in position on the front of the foam core, and use duct tape to fasten the Dacron on the back side of the foam core. Cover that with an outer fabric of your choice, again using duct tape to fastening the outer fabric to the back of the foam core.

Mount to the wall using heavy duty Velcro.

I have six of these in my living room. Most people think they're just decorative panels.

My 30"x30" panels costs about $15/ea, with the largest variable in the price being the cost of the outer fabric.

One problem that I have is that one ref. point will be on a sliding glass door covered with vertical venetion blinds. Maybe I can build something on a floor stand. Any ideas?

oops, I responded too early to these useful suggestions in my previous post. They`ve all been useful and will be concidered. Thanks for your input.

Tvad's suggestion is a good one, because you can tailor the look of the panels to your aesthetics and room decor.

Does the bookcase filled with books thing really work? If so, would it be better than, say Tvad's homemade panels? I have two bookcases full of books that I could use for this purpose but before I was thinking of draping a cloth over them so they'd be less distracting.