[Jeroen] built his spin coater out of a brushless DC ... motor controller, and an ESP32. A rotary pushbutton and an OLED form the user interface, allowing the user to select the speed and spin ...

En route to getting the off-the-peg DC-51 motor speed controller to better suit my small milling machine, I had a go at working out what the circuit is. Approx circuit of DC-51 motor speed controller ...

and works a lot like any other brushless DC motor with an ESC (electronic speed control) on something like a drone or other UAV. But while the unit can be given throttle or speed control signals ...

Arduino-sourced PWM-based speed control is a bit more tricky ... someone called H Holden has published a detailed analysis of a mosfet chopper style dc motor controller.