I was lucky enough to find an NES Classic in store. Walmart worker was a bit shady, felt like he was reluctant to get me one out of inventory in the back but there was another worker there with him that may have been his manager. So after a long awkward pause, he was like "uhhhhhhhhh, hold on", then goes into the back and comes out with a mini. I just wanted to share that story even though has nothing to do with the DIY controller. Okay, one more vent story. I bought the Emio Edge joystic after reading that Emio had fixed the controller to work with the mini. The first Emio Edge I had acted wonky. There was a long delay in movement and button clicks. The turbo controls didn't seem like they did anything. I returned the first one and received a replacement. The second controller responded spot on to movement and button clicks, no noticeable lag. The turbo controls actually worked, the LEDs lit up and the rotary dials controlled the turbo rate. However...
Lame brain ideas that stew up in my noggin to impulsive projects. Ideas of non-existent dohickies or nice to have things. Sure you could buy something already made but there is more fun in trying to build it.