I did some math and here is what I got, to make it to where atleast the front of it is SCALED to the original it will have to be about 8.25 in tall and 27 in wide at the base and 31.5 in wide at the top....
Maybe Scaled exactly wont work out... The bottom portion has to be atleast 3 inches tall to hold the motherboard, PSU and fan...
I can still make it look close, it will have to be not as wide, though... The joystick can sit in a void over the motherboard.

Here is a picture of what the footprint of the bottom would be.
18 in Wide x 17.5 in Deep x 3.5 in High

Here is the monitor I plan on using, I'm removing the base, of course, the speakers will go under it.
The top portion will be wider than the bottom due to the angles that exist on the bottom.
I decided to make the whole top portion fold up instead of leaving part of it down because that would add quite a bit to the width of the thing.
I'm getting wood tomorrow for it, and I'm starting to build it. Harbor Freight is having a huge sale this weekend BTW, got a nice jigsaw today.
Any suggestions on the design or materials?