Sorry, I can't take credit for it. I think I read about it in Carl Ehwa's The Book of Pipes and Tobacco, I'm not sure -- but it's not my idea.
It's easy to make too. Just wrap the pipe in a chamois, stitch around the pipe's outline with heavy thread (LOL: I used 50lb. test fishing line!), and trim the excess. Don't sweat the fitting -- the chamois shrinks in time with all the heating -- but make some allowance for it (see claw above.)