Thanks to 3D printing and inexpensive controllers, a robot arm doesn’t need to break the bank anymore. Case in point? [Build Some Stuff] did a good-looking compact arm with servos for under $60. The arm uses an interesting control mechanism, too.

Instead of the traditional joystick, the arm has a miniature arm with potentiometers at each joint instead of motors. By moving the model arm to different positions, the main arm will mimic your motions. It is similar to old control systems using a synchro (sometimes called a selsyn), but uses potentiometers and servo motors.

An Arduino handles reading the potentiometers and driving the servos. Still, we couldn’t help but think you could forego the controller and simply use the pots to generate pulses directly for the servo motors — maybe use a  555. Of course, having an Arduino means more flexibility in the long run, so it makes sense to include it.

Of course, servo motor arms aren’t usually good for big jobs, but as a demonstrator, it works well, and you can’t complain about the price tag. Wow, building a robot arm is easier than it used to be. If you prefer a more conventional controller, there are, of course, many options.