LEGO MINDSTORMS Robot Inventor
This simple model with two motors lets one motor act like a manually cranked dial, and then powers the other motor to make it automatically copy the position of the first motor. Twist the black dial and the teal one will turn to match it.
Two programs are provided to show a useful trick with motor control to make this work better, which can come in handy in other models you might make.
For a 2-axis version of this idea, check out the Copycat Hand.