[pugs]

I would use brass or plain steel tubing for the cylinders and just hone out smooth (oil will coat inside and paint outside for rust proofing) For the Rod I would look at precision ground stainless, should be plenty smooth enough (most anyway, some ground stainless rods aren't the best and would need polishing) and the stainless would keep rust away. Much cheaper and easier than zinc and chrome plating for what it is.