When I was building my fix it Felix cabinet, my intentions were to use a standard Arcade power supply. 5 V would run the single board computer, and the 12 V could be used to power the monitor sound amp etc. I had heard rumors in the past that switching power supplies can be noisy but OMG the whine that came out of my amplifier was unbearable, and facilitated my own construction of a much cleaner power supply.
For my project I required approximately 4 A of 5 V DC, and approximately 3 A at 12 V. I purchased two separate power supplies, one for the 12 V feed and the other for the 5 V requirement and laid out an arcade styled power supply box with standoffs for my PCBs. Enjoying actual digital readout, I incorporated those to the front panel, as well as moving the voltage adjustments from each board to the front panel. Just for fun, I Included Sour Bill, as my power indicator on the front, and Vanellope von Schweetz on the back panel. When illuminated with LEDs, you can verify the power supply is on when opening the coin door. 123D files are included for remixes, as well as Vanellope and Sour Bill drawings