As far as painting the inside of the case, here's what I do.
Pull everything out, of course.
I take off all plastic pieces, all wires/LED indicators, the power button and so on. All I have is the metal frame of the case when I'm done prepping. Then, use that new green frog tape to tape off any areas you don't want sprayed. I use the frog tape from Lowe's now because unlike the blue tape, it won't pull the paint off of the surrounding area.
Prep the motherboard tray/all metal areas to be painted by sanding it with 320 grit paper. Then 600, then 1000. The 320 will leave swirls in the metal. You want to get that grayish protective coating on the metal mostly off of it. Then use the 600 to reduce the swirls a good bit. I use 1000 as a final step, but you don't have to. The primer will do a good enough job on it.
I will then take the case to the tub and wash it. Then out to the garage and use my air compressor to blow out most of the water. I will then allow it to sit overnight with a space heater on it to finish the drying process. I will also set my cans of paint in such a way where they are also warmed up by the space heater. Mine has a digital readout, so I set it to 75Â°F and allow the paint and the case to be the same temperature for when I start painting the next day.
I will use one of the motherboard standoff's with a small washer on it to prep the holes on the mobo tray. I'll take a small amount of Vaseline (it doesn't run) and put it lightly on the threads and the side of the washer that faces the mobo tray. I will then screw the stand off into each mobo standoff hole in the tray. I will add a bit of Vaseline to the standoff/washer each time before screwing it in lightly...you don't need to tighten it down... and you want a very thin amount on the washer. This will leave the Vaseline in the hole and for a small area in a neat circle around the hole. I do this because I've found over the years that if you paint into the standoff holes, when you thread in the standoff, it will crack the paint all around that hole and when the standoff is tightened all the way down, it eats into the paint causing it to chip off. Once the paint is completely
dry/cured, I simply wipe off the Vaseline. It will have paint over it, but it will wipe right off leaving a nice, clean circle. And I do this for every single hole in the thing. Like the Antec 900 I did a couple of years ago. That SOB had a LOT of holes to do because of how the drive cages are done.
I will then use Rustoleum's self etching primer. If I can't find that, I'll use the primer that converts rust to primer stuff. Make SURE you're painting in an area above 70Â°F though.
Then, I will finish up with the Flat Black or maybe a semi-gloss. I like flat black myself, but semi gloss does look good in a case with lighting and water cooling IMO.
This may seem like a pain in the ass, but you only have to do it once. I'm a detail oriented person and I DON'T like having to do the same job more than once and I don't like half-assed work. For a little extra effort in the beginning, you can have a nicely painted case where you can swap out motherboards five and six times without worrying about your paint coming off.
Here in the next few weeks, I'm going to do this same process to yet another case. My Cooler Master HAF 932! That thing will probably take a couple of days to get done properly. I checked into powder coating it and it was going to be upwards of $100 to do it. But I don't have many places near me that powder coats either.