Merry Christmas to all.
Paul Warburton uses old pieces of fan belts, and glues then on with rubber cement...works like a charm.
Here's my patentable, removable bumper that I will divulge in the sake of preservation. When you have top or back off, glue on one of these inside the bass at the points where you want to stick the bumbers. Line the bumper underside with felt so the finish will be unharmed.
http://www.pennstateind.com/store/emag34.html