FILLING THOSE CAVITIES...

Questions come in as to how to effectively and permanently fill voids (holes) in the bodies of harpmics -whether caused by damage, absent and unneeded set-screws, or gaps around modifications in the zinc-alloy shells. You would want to use a material that's easy to apply, will stick to the shell's alloy, and can be tooled much like the metal it's applied to. Maybe you've found solder won't adhere to the alloy and Bondo-like fillers aren't hard enough...
Suggestion? One solution would be to use one of the metal-reenforced two-part epoxies found in automotive and hardware stores. JB WELD is the one I know best, altho there are "house" brands marketed through various chains, such as CAR-QUEST. These epoxies have more structural integrity than most "plain" two-part solutions. They also can be filed, drilled, and sanded with less of the "tack" of typical two part epoxies, while painting them presents no significant challenge. Good stuff to keep in your toolbox. WARNING! Not for use in home dentistry...