The fatigue cracking is a concern, for that reason I would not use copper, there are better materials out there (even if copper was used for a long time...)
How about some copper nickel alloy, it polishes up to a combination of copper and stainless, looks like neither one or the other, looks about half way in-between. It is easy to work with like copper/unlike stainless, is not prone to cracking, and will not rust. It is not available everywhere, but you can get it from these folks, sold as "Cunifer"
http://www.fedhillusa.com/ At first I thought it was pretty expensive, but after using it and also stainless the slightly higher price of the copper-nickle line is well worth the ease of use and reduced frustration. I don't plan to use much if any stainless line any more.
You can get it cheaper on ebay from the UK, possibly cheaper than stainless?
http://shop.ebay.co.uk/items/_W0QQ_nkwZkuniferQQ_armrsZ1QQ_fromZR40QQ_mdoZ About half price of fedhill after figuring exchange rate and shipping. I'll try them when I need to order more. The folks at fedhill are nice, but some competition would be good for the prices (but obviously not for them).
Grigg
