No...no, no, no. It's going to be a PAIN to seal everything off right. If it were me and I were so inclined, I would remove the casing on it, which is very easy and perfectly safe if you know what you're doing, and then paint that. Or, if it was a standard ATX size, I would get an aftermarket plexi casing.
Carter, this is one of those mod projects where, if you have to ask how to do it, you're not prepared to do it.
What I would do in your position, is head over to mnpctech.com and order up a sheet of vinyl stick-on, and use that to cover the top, bottom and sides. Cut a hole for the fan opening (if there is one), and you are finished. Watch their tutorials on the subject. The vinyl can also occasionally be found at auto parts stores and arts and crafts places (but probably not the cool patterns).
I'm using that material right now to dress up the side panels on my girlfriend's rig...and my mouse...and my speakers...and my front bay devices...