My son is restoring an older Mercedes and delved into rebuilding the seats. A suggestion was passed on to use swimming pool floats - the tube types that are popular when wacking your buddy. The things are cut in various sections, some as short as 4 inches, and then forced down the center of the circular springs. I had heard of using foam to restructure the circular springs, but not the pool tubes. He claims that the support in the springs can be modified to suit the user by varying the length of tube that is inserted into the spring. Anybody out there use this method?