“Micro-servos are great devices perfect for adding motion to your projects. Unlike steppers, they can be controlled directly from your Arduino or other favorite microcontroller. Most servos are limited to 180 degrees of motion. This allows microcontrollers to know the exact position of the servo’s shaft. You can find continuous rotation servos, but if you have access to lots of cheap micro-servos of the 180 degree variety, it might be helpful to learn this quick hack to make them continuous. “