I have finally completed my MAME cabinet after several months of hard word (tbh, and a lot of waiting). So, here is the completed cabinet, and some resources to help you build your own.
The final piece to the puzzle was the motherboard. While installing some new LEDs to the coin door, I managed to burn out the motherboard audio. Luckily, I have a 1-year warranty; unluckily, it was two days after the 30-day return window for Newegg. I contacted Asus for a replacement, they told me Newegg would handle it. It took about a month to get in touch with Newegg who told me Asus would handle it. Asus was much faster responding, and I finally got my replacement installed and working.
Check out the resources to build your own MAME cabinet