Real size arcade machine for two players I made using a Raspberry pi 2 with emulation station and retropie. I know it has been done several times but here is my take on it.
It uses two controllers and the driver can be downloaded from: https://github.com/digitalLumberjack/mk_arcade_joystick_rpi
Excellent driver for two players. Each player has 6 buttons as well as a 4 directional joystick (although I´m planning to add 4 extra buttons for mame games). In that link you´ll find how to connect the buttons and joysticks directly to the pi, which is rather convenient since you don´t have to buy any kind of external serial adapters.
Guide on how to install emulationstation and retropie:
Paint: Alquidilic paint blue color
Size: 170x47x40 cm.
Music by Eric Skiff
What I used:
Raspberry pi 2 with 8 Gb micro sd card.
2 four directional joysticks
12 arcade buttons
1 pair of speakers
1 monitor 19´´
1 hd to vga converter
Cost of the project: 200 dollars (although here in Mexico the components are kinda expensive, I´m sure you can get better prices in the US or anywhere else).