Ok I want to spray the inside of my case black, but i don't know where to start... Like which spray paint would be best for this?? should I coat the inside with something else first or what??
Just be wary of painting. Wait at least a month before putting your stuff back in so the paint can cure properly. Also google a bit and find a guide.
Most important thing is to paint in a CLEAN area with no dust. I painted my old case and F***ed it up. I did everything I could but those dust particles WILL F*** your paint job up. I then bought a new case because of it.
I would suggest taking it to a professional place or building yourself a clean room before painting.
If you are going to powercoat you have to strip it down to bare metal, acid etch/sandblast etc. It won't take over existing paintwork. Quite a mission.