Ok so first thing first. Lets make an NES PC. Hatsuli's NES PC
was of great help during the planning of this project. However, we are specializing this NES PC to be a console, while hiding the fact as much as possible that it is a PC. Lets start with the NES.
First take apart the NES by taking out the bottom screws in the case. Continue to disassemble it until you have all the "guts" of the system out, leaving only the controller ports, which we can simply disconnect from the NES hardware. Remove the controller ports and put them aside for later use. We will also use the mounting bracket and buttons from the power button assembly. So save these as well. Now that your case is gutted, simply use a dremel and remove all the posts in the case except for the four corner posts and the two posts that hold up the power button assembly.
This should leave us with a fairly open case in which to build inside.