air brush now

I have seven computer cases that house my electronics for my music/video editing studio, general computing, mobile recording, and home theater.

I would like to decorate these cases, which are roughly the size of a rather large shoebox. Heat is NOT an issue.

What I would like to do is decorate each of the cases with characters from anime, one cast of characters per case…in a design dedicated to particular series of anime.

Air brushing is prohibitively expensive, so I am wondering if I could do decoupage on these metal surfaces? If so, could you please give me advice or a website or book that could help me with this procedure?

Thanks a lot.