Originally Posted by Ceadderman
Unless you have broad patches of bare steel there is no reason to spend money on the Primer. The reason being is that your paint has a good chance of being too thick. On the MoBo tray that's not a big deal especially if you use standoffs to protect the threads. However the door jambs can't have paint buildup(as well as any place that has friction) because they will have a tendency to mess up your topcoat when you remove doors or slide HDD trays in or re-installing the thumb latches.
Sorry, but you are completely and totally 100% wrong. The paint would only end up too thick if you use overly heavy coats. 2 light coats of primer and 2 to 3 light coats of color will NOT build up too thick to have any adverse effect.
And yes, you do need the primer. The inside of a case is bare metal, especially once you use a scuff pad. Without the primer the paint won't properly adhere to the surface which is what will cause it to scratch or peel when you install/remove hard drives, optical drives, side panels, etc.
It isn't "wasting money" to use primer. It's a waste of time and money to NOT use it.
I've painted over 50 cases over the years, all but two of them using primer. All of the ones with primer look just as good 3 or 4 years down the line as they did when they were finished. Most have absolutely no scratches or other blemishes. The few that have any are due to the user not taking a modicum of care when working inside the cases and mounting hardware. The two that primer wasn't used on (and that was done as a test to see how well that worked), using the exact same top coat paint as the ones with primer, and allowed to dry just as long (2 weeks) before assembly started scratching from the very beginning of installation of the drives and looked like crap within a couple of days. You can do what ever you want, but please do not recommend that others follow your poor advice. Anyone who knows anything about paint knows your advice is incorrect.