I built this "X-men" arcade machine with my daughter over the course of about two years (it shouldn't have taken that long).
It was a really fun project and we are extremely happy with the way it came out.
A few things about this instructable:
1) I'll be more precise with instructions for the actual building of the cabinet than I will be with some of the particulars regarding the internal electronics. I'll still have a lot to say, but since everyone will have a unique monitor they want to use, a unique sound card they'll want to scavenge, and varying degrees of skill in electrical work, so I'll be more broad in my instructions than elsewhere.
2) This cabinet can be used with a number of game systems. We chose an Original x-box, circa 2003, that we had been using as a multimedia center. We loaded Coinops7, an awesome arcade/home console emulator. It works great. You have other options, though, the biggest being MAME, which runs on a windows.
3) This project will take some thinking on your part. I'm going to show you how we did it. You'll need to work around the fact that you've decided on a different monitor, different PCB (joystick or whatever), or a radically different audio system.
4) We built this machine by looking around the internet, seeing different ideas, and then making our own design. If it looks like machines you've seen, that's because we saw those machines and wanted to copy them! None of what we did with this instructable would have been possible without all the work put into the hobby long before I came around. So thanks to everyone whose ideas we tried to emulate.
5) We didn't always remember to grab the camera. In some cases, you may see pictures that are slightly out of order--pieces that are already painted, parts that haven't been added, etc. That's because we went back and took pictures after-the-fact.
Have fun. We sure did. It's a great way to spend months of your life building a machine with less brains than your flip phone.