This is a fairly easy way to etch metal for your next steam-punk project.
There have been many articles written on this subject covering the process of photo-etching, however I would like to describe how I have made use of a different technique which makes the whole process of home etching a much easier undertaking as it does NOT require any photographic steps.
Learn more about Brass Etching for Beginners
How to : Electrolytic Machining of Brass
How to : Electrolytic etching of brass for Moleskin notebooks