alanint,
I found a couple links so far about home anodizing. Looks like fun! And this might be the culprit--as far as finishing pot metal guns. it fits all the criteria: It can be any color. It offers corrosion and abrasion resistance (up to Rockwell 70!). It can be rubbed out for increased gloss. And any dimension it adds, typically up to 4 mils, dimension to the parts in a controllable way. Interesting...I already have some expendable parts for practice/testing, and most of the equipment and chemicals; just need to pick up some black and dark blue Rit dyes. What do you think?
http://www.warpig.com/paintball/technical/anodize.shtml
http://www.defelsko.com/applications.../Anodizing.htm
DP