1.   He tried polyethylene foam, but paint did not adhere to it, so he laminated a sheet of paper to the shapes.

2.   I tried foam on the top as a cushion, but it deteriorates quickly.

3.   Manufacturers also tried foam a few years later, but dogs ate them.

4.   The trend toward comfort is likely to continue, as different foams are tried inside shoulder pads, and the air bladders in helmets are adjusted.