This is the custom circuit board that goes inside Stewy's base. It routes power and signal from the ESP32-S3-Nano to all six MG90S servo motors through a set of JST connectors. It was designed specifically for Stewy V2 and is manufactured by PCBWay.

You've got three options. The bare PCB is just the board itself, free plus shipping. The unsoldered version comes with all the components you need to populate it yourself. The soldered version comes fully assembled and tested, ready to plug in.