How I did it.
1 Raspberry Pi
(in my case a old 21´´ TFT 4:3 with DVI Input) which made it easier to connect it to the Pi
1 Old Wardrobe (or a lot of ply wood)
I removed the silver coverage from the wardobe cutted out the arcade case and glued the silver coverage on again.
1 PC Speakers
1 ATMEGA 32U2 Board (e.g. NooGroove: see ebay)
1 Arcade Joystick from ebay
1 xArcade Trackball
A few Arcade Buttons
1 green LED Stripe (for illumination)
I used two existing Projects:
First Kade loader
with this one you can progamm your ATMEGA32U2 to emulate a Keyboard when a Button was hit.
This is a great Project from Shea Silverman
It's a multi arcade machine emulator (and much more)