Ok , After you have removed everything from inside the case, You will need a scuff pad, You should be able to get one from your local store or local car body shop.. Scotch brite pad, the one your mom uses to scrub her pans.. There are green scuff pad. Now make sure scuff everything real good, OR the paint won't stick. After you are done scuffing everything, Make sure you blow everything out, Or you can use some cleaneez..Next mask everything that needs to masked off. Next is the paint, If you want a high gloss then use
RustOlium... There are allot of others that would work as well. When spraying with can spray paint try to stay at least 8 to 12 inches away from the case.
good luck.