I already have 2 zappers. They are from ebay, The World's Smallest Zappers. I kind of modified them, cut the wires at the ends to expose the inner wires, then attached those with my own aligator clips to pennies or copper foiling footpads.
The nice thing about the ebay zapper is that it is wearable. Awkward. I have to Nexcare tape this and that, including the battery, but it works.