Ok guys this is getting far too complicated as Supra says ... hopefully this will help.
I've put a pic of the ring I've just made ... it cost pennies (dimes?) and all the parts are easy to find and may even be kicking around your yard.
Tube = neoprene fuel line as used on lawn mowers
Copper = I used some old cooker wire but you could use brake pipe or any other copper tubing.
Zinc = I used a bit cut off a boat corrossion anode which is pretty much pure zinc, I just hack sawed some off and filed it to shape. You can also find zinc on old style torch battery cases or anything galvanised (zinc plated) such as nails.
You act as the catalyst between the two different metals and a small voltage will pass through you ... when you sweat the saline solution you produce will simply create a better conductor. If you want to fill "a" tube with saline leave the other empty ... this will cause "you" to be the last link in the circuit. I guess theoretically you could use two of each metal with saline between to conect the "cells" in series, leaving the last tube (at least half circumferance) to bump up the voltage and again use you to complete the circuit. However, as Supra says, it's probably over the top.
Anyway hope the pic helps ...
Ivan