ok had a thought of using aluminum conduit 1/2" as my negative. basically tube design. tubes being negative and ss rods being positive. I have seen post on the boards saying not to mix metals in the cell but i have also seen post saying negatives can be a softer metal. I of course like most of us am trying to be cheap. looking at most tube designs they use all tubes but wouldn't the inside of the middle tube kinda be useless.