Painting my HAF 932 from the inside, do I really need primer?
Or could I just sand the whole thing, apply a couple of layers of undercoat and a couple of layers of black paint? Using primer just seems like a huge waist of time.
If I read this correctly ,you want to sand the whole inside then apply 2 coats of undercoating and then two coats of black paint as opposed to one coat of primer and one, possibly two coats of paint?
If priming is a waste of time what about all the useless sanding and undercoating?
One primer and then paint it. if it comes out well then you are done , if not apply another coat of color, don't sand and all that bs.
Actually, I'd advise you to check out mnpctech's tutorial on case painting. Its not as easy as it looks, and these guys know their stuff. You certainly don't have to be as elaborate as they are, but the basic techniques are solid.
In answer to your specific questions, you should take the case down to bare metal, and use a self etching primer. I use automotive paint for my mods, automotive primer works well. Specifically I achieved results similar to what the mnpc experts can do with rustoleum brand paint, which runs about 5 bucks a can at Walmart. The other brands mentioned in the tutorial are quite pricey and not available in my area, except in specialty paint stores.
In my experience if you just begin painting over the original paint, you aren't going to get the results you're after. You are going to get an orange peal, chipping and peeling mess. I tried, and failed.
I have a recent mod I am working on, I decided to paint the interior without primer. I ended up with a rough, paint spattered look that I found strangely appealing but it definitely wasn't what I was after. Regardless, its just the interior so I'm not too worried that my sister is going to open the case and closely examine the paint job!
The bottom line is, if you intend to paint a case it will really depend on how much effort you're willing to put in to do it properly.