How would you do that? Please give your examples...
I know that Hulda said no metal on top of the zappicator... so, if (theoretically) I make the zappicator using the South Pole speaker (or transducer) and then instead of using it for food/water will use it for some metal objects, then the magnet might change its polarity....
After that I will be able to use it for food/water/body, etc.