A: Go outside, and find either a nice large rock (granite and other hard rocks work especially well), or just the concrete curb by the street. Hammer the rock or concrete for a while to break up the varnish surface. You can also use something like a belt sander or grinding wheel to rough up the surface a bit first, speeding the process, but it’s the impacts from hammering something like that rock or concrete curb that will break up the smooth hard surface to a worn rawhide one.

You can also, if you’re in a hurry for a soft mallet, use a rubber band, wire, packing tape, or whatever you like to hold a piece of ordinary leather stretched over the head of the mallet. It’s not quite as controllable in some situations, but it works.