The Automatic Print Ejector is pretty much taken straight out of a [Buster Keaton] movie. It’s a series of scissor mechanisms with a 3D printed boxing glove on the end, driven by a stepper motor.

Charles Vander Woerd, a superintendent at the American Watch Co. in Waltham, Mass., invented this machine in 1871. It was the first automatic lathe to make watch screws. Fed rod stock by a machine ...