I found the article about the penny ring of power that DLD mentioned. Here it is.
I haven't tried a zinger and didn't want to invest in the suggested materials, so I pondered some alternatives. What common, cheap things are sources of zinc and copper?
Eureka! U.S. pennies.
Pre-1982 they were 95% copper and 5% zinc (with some tin in the earlier years). There's your copper.
Newer pennies are 97.5% zinc and 2.5% copper. Bingo, there's your zinc.
File or sand the copper coating off the zinc penny and sand any oxidation off the copper one. You could use a new copper-coated penny in place of the old one if it is clean enough. The plating is enough to work. For long use, the old, 95% copper penny would be preferable because it can be sanded for cleaning.
Attach however you like. It could be to the underside of one of those wrist straps that are popular, a homemade thing, whatever. Use your imagination. You could even drill holes in the pennies and sew or tie them to your strap or ring.
Several could be used on each side for better contact. I haven't gotten that far yet, having sanded the skin off the edge of my thumb doing the first one. Be careful.