This is a demonstration and experiment kit for PID tuning experiments.
Circuit design was done using the software named Fritzing, and the schematic is available in PDF format.
The complete CAD design is available as a SolidWorks 2016 model from here. Additionally, 3d printable parts will be available as STL files from here
The complete firmware is available here. The microcontroller used here is ESP32 Dev Board. But it is possible to change the firmware a little and use it with another microcontroller.
Can change following variables to alter the kP, kI and kD constants.
//PID constants
double kp = 15;
double ki = 0.01;
double kd = 0.05;
You can build and upload the firmware using PlatformIO.