100 Polyurethane from Walmart ?

What are you talking about? Please provide a link when reffering to another site. I couldn't find anything like this on Walmart's website.

No different type of foam altogether, accoustic foam is a different formulation and completely different cell structure.

Etran, you're better off with high density fiberglass as sound absorber than most foam products. Both Owens Corning and John Mansfield make these panels in 4X8 feet and 1' to 6" thick.

This high density fiberglass is what my room is covered in and what most recording studio's use.

The down side is the cost of the rail system that allows for fine finish of acoustic cloth to cover it all up.

These mattress pads do make excellent packing material for components. I have sent 2 CDP's to europe using old pads cut to fit as packing. They arrived in pristine condition despite being handled bu US and European postal processors.

I have used the foam pads from walmart and they work great. Best value, twin size, I use them three thick. I use 1 by 5 inch pine frame backed by 1/4 inch luon. I wrap them with black twin bed sheets from walmart $2.65 each, stapled to the back luon. They are 6 ft by 3 ft and cost me $50.00. I mount them on ceilings and walls using simple brackets. Free standing panels are drilled from the back with a hole saw, opening the back. I roll full or queen size pads , like a cigarette, stappled around a wooden closet pole, wrapped in the same blk bed sheets and mount them in the corners of my room. I also use them hidden behind my wall hanging carpets and ta pastry. The panels are 1/4 of the price of finished( wrapped in fabric )sound panels.