The cheapest robot arm that still teaches real robotics is a compact 4-axis servo arm with a small gripper.
The cheapest robot arm that still teaches real robotics is a compact 4-axis servo arm with a small gripper. It will not lift heavy objects, but it can teach joint control, saved poses, calibration and simple pick-and-place.
Do not make the links too long.
Do not make the links too long. Short links reduce torque requirements and make cheap servos less frustrating.