I would prefer to avoid acid if at all possible.
Have you looked at electrolytic etching ? http://www.greenart.info/galvetch/advan.htmSteve
chisel it only problem though is that you have to be freaking good at engeraving stuff with a chisel
You may be able to use ferric chloride. It's toxic, read MSDS datasheet before use. Also might not work, but worth a shot if you have some around. Sharpie marker acts as a pretty good etch resist. Try it on scrap steel first.
There is an instructable on salt water etching look it up.