Here is a project I did a while ago: after seeing some videos and reading some articles about people using a Raspberry Pi to play retro games, I decided to build my own custom fullsize bartop arcade cabinet.
I did some research and decided I would need a Raspberry PI 2B, an I-PAC 2 interface, to connect the joysticks and buttons, and RetroPie software as the main parts to make it work.
For the cabinet I decided to order pre-cut MDF panels and acrylic sheets.
After assembling the cabinet, I did a test with the monitor and RetroPie software installed.
Note: I used a monitor with an aspect ratio of 4:3 to better match the resolution of retro games.
As this was succesful, it was time to spraypaint the cabinet.
I installed the joysticks and buttons and connected them to the I-PAC2.
Then I installed the speakers and created a custom marque around the Metal Slug theme.
I added the marquee with backlight, a power-switch and a small fan to blow out the heat of the monitor.
And the project was finished! Here is a video of the building progress with a demo at the end.