Is the case metal or plastic? If it's plastic use Krylon plastic paint,If metal you can use pretty much use any spray paint like enamel or something similar.
Same thing here my 1 case came out fine because it was metal,But as soon as i tried painting my face plate for my old burner it started to eat it all up,It looked like hell afterward's.
Take the whole external casing off. Pull out any plastic activity lights and, rip off any intel inside stickers. Wash the case down with windex and than water, wait until it is dry to start painting.
Do not paint in the sunlight.
Do not over do it. You will be left will sh!tty looking blotches and bubbles.
Go over it with a light mist. With a nice back and forth motion. Repeat until it looks good.
Let it dry for 20 minutes.
Get a can of Clear enamel and go over it with a light mist, a couple of times.
After that let it dry for 1 hour. The paint will not fully cure for 4 days.