A long time ago I took apart an NEC PCFX system to see what was inside. Answer: not much! Check out this madness, the system's made from some 12 different panels, covers, guides and shields, countless screws and a wickedly convoluted assembly procedure. The only easy step is the first one, removing the side panels. After that it's all tortured logic and interlocking panels and strict order of parts removal. Here's the visual journey, and I apologize for the quality of the pictures. I think I was working in the dark or something.
It was a long time ago, I was young and stupid.
One of the mainboards with three expansion ports on it, each facing a different direction for no good reason. The front one was for memory cards, the rear for the SCSI adaptor, but the botton was, AFAIK, never used.