Found my case over christmas ...and i enjoyed the chocolates
Firstly, be very careful if you are cutting holes; it will crack very easily.
Secondly, do not paint the outside. Start by painting or otherwise applying the logos, port labels and so forth inside the box. Then finish with an overall coat of paint also inside the box. You will end up with a professional-looking high-gloss finish and an impervious paint-job. I've done this sort of thing a few times, and it takes a so-so DIY project and makes it look great.