I had a discussion with someone about spraying some boxes previously, the main concerns are: Making sure you use a Flame Retardent or Non-Flamible paint Making sure the paint doesn't cause corrosion to either the case or components. (In fact if your cases stinks of freshly sprayed surface, make sure you air it a while before puting it back together.) Making sure the paint sticks to the surface (Since boxes can be metalic and plastic, you might find some paints react funny in some cases. Also check that it "Peels" and doesn't "Flake" if the paint should come unstuck, the last thing you want is "flakes" being sucked into your fan units.) Other than that, you could try some Case testing, pickup some old Computer boxes from either a second hand shop, or even dumps (even Yard Sales etc) Give them a test paint to perfect your decoration and knowledge of which paints to use. If you end up with 20-30 cases painted you can either talk to a Gallery to show your work and/ore sell them on Ebay.