Two player Neo Geo control panel layout fits in a space way smaller than anyone would actually want to build on, so that part is not really important.
Seriously reconsider what you just said about a 17" monitor, unless you make a 1 player mini cab then a 17" monitor is going to ruin your entire project. Something shaped like TMNT with a 17" monitor in it would look like Kentucky Fried Cleveland Steamer.
For most people the display should be the most expensive part of the cabinet. A used 21" CRT monitor is only about $100.
If you really don't want it to look too much like a Mame cab then you need to rethink everything, because right now this is headed for crap-mame territory. Every machine even REMOTELY shaped like a 4 player TMNT has a 25" monitor (or larger).
By six inches, I meant the CP would be shrunk by six inches as well. Im only going to be using a 17 inch monitor (initially anyways) so I dont need the near 3 foot width the CP offers nor the nearly as wide cab itself.
Other than starting with another 2 player of similar design, any ideas on how to reduce TMNT 4 player specs so it doesnt look too much like a MAME cab? (bear in mind as well that I will be using the neogeo/SF2 button setup, so I need a little bit more realestate on the CP than a 2 player version of TMNT)