This controller was based on the Phob PCB, but instead of using a 20 dollar Teensy 4.0, it uses a Raspberry Pi Pico which only cost $4. The Pico is limited to only 3 ADCs by default and the GC has 6 analog signals. So instead of using ADCs for the hall sensors it relies on the DRV5057 sensor which outputs PWM. So only two inputs from the sliders need ADC inputs. It has a LM4040 for a voltage reference to add stability to the ADC reading. Normally the Pico is too large to fit anywhere within the standard GC PCB. But if the board is chopped it leave just enough pins to get by (sort of, more info below), and just enough space to fit between the L and R sliders. It also has a USB C port near the handle so the board doesn't have to be completely removed for programming.
In addition to this the board has resin printed mounts that mimics the potentiometer of the original Gamecube controller. They don't require glue on the stickbox as they clip on to lock.
The Pico GC also has tactile switches instead of the normal membrane pad for the D-Pad. The membrane pad is completely deleted and these are soldered directly to the board instead. The part number on these is KSC221JLFS, they are avaliable on Digikey as well as my store if you'd like to support me.
Ultimately, this was mainly just a test controller before moving over the the RP2040 standalone just to see if it was possible to be done. I DO NOT recommend getting one of these printed and testing it out expecting a finished product. By default reading the PWM sensors with standard library functions, I was not getting consistent enough readings or high enough performance for Melee/Basic use. There is a lot that needs to be done on the software end to make something like this work properly. Additionally there was a small over sight when I did the board and forgot the data pin. So for now the LED pin has been powering the data communications instead of rumble, but it should be swapped to another pin to be properly used. I would suggest using one the L or R digital pins then compensating them in software. The capacitors around the stickbox and for rumble should also be relocated to not interfere with the Shell and Stickbox (I had to manually relocate them on this PCB).
The board files are open source under the Phob license feel free to download them and take a look. I would edit them with the changes mentioned above before submitting them. Also I would not submit board files unless you feel comfortable with hardware and software development. The next board will contain the RP2040 integrated on the board, and would wait for those files instead.
https://github.com/SimpleControllers/pico-gc