We used to do this back in the days of lan parties with our PCs. It used to be soooo punk rock.

You need a bottle of RIT fabric dye, a ****-ton of ammonia, and a car battery with two leads attached. Put the **** in a bucket, fill it with liquid, stick the leads in there, and wait a day or two.

Or you could spend 20 bucks and take it to a powdercoater.