You could try black anodising, it's not a difficult process and by varying the technique you can vary the smoothness of the finish. Here are a couple of sites with info on anodising.
http://www.sca.unimelb.edu.au/va/metal/tech/anodfr.html
http://www.focuser.com/atm/anodize/anodize.html
Apparently Dylon Ebony black Multi Purpose dye (MP8) (not cold water) will work for anodising.