Added a switch-hole on the bottom (very small) to allow for a small switch.

I was using a USB controller for my build, and so I had to solder the leads directly to the USB pads on the Pi Zero. I wanted to still be able to use the USB if I needed it though, so I added a very tiny (3mm I think) switch, to switch between the controller interface, or whatever I connect to the USB.

I know my print in the picture is bad, I was calibrating a new printer, and used it as a test to see if it would fit. The original creator thought it would only fit the original NES controllers, but it does, in fact, fit the new USB ones as well.

NOTE: If using the cheap USB controllers from China, the D-pad sucks... The last pictures are step-by-step how to fix it. I bought sticky-back craft foam from Michael's, and cut tiny squares. Then I used a razorblade to cut them down to about 1-2mm tall. I stuck them in the "angles" on the D-pad. This fixes the problem, and the controller works like a dream.

I have also included photos of how I wired the controller.