The hardware design is relatively simple. Since it is a single-axis tracker, it only needs one degree-of-actuated-freedom. We also need the ability to orient the system according to the latitude to square up the system to the axis of the Earth's rotation. There are 5 3D printed components in this first design:

• Bottom plate
• Top plate
• Shaft coupler between stepper's D-shaft and the M5 threaded rod
• Motor mount
• Threaded rod nut mount

All parts are assembled with 3 unique hinges so that hinge slowly rotates as the stepper motor drives the threaded rod. This prevents back-driving so that no power is required to hold position, and the stepper motor has a huge amount of mechanical advantage. Even the small, relatively low power 28BYJ-48 stepper motor is capable of actuating a large amount of weight. The hinge only needs to move at 15 degrees/hour (360 degrees / 24 hours), so speed is not important. In fact, we want the rotation to be very smooth so as not to disturb the picture. The extra degree of freedom for orienting the hinge to be parallel to the Earth's axis of rotation is assumed to be in the tripod. Note that the tripod shown below is not quite strong enough, so I will need to get larger one. A COTS ball mount is also used on top to allow easy mounting of the camera and to avoid interference with the threaded rod.

An M5 nut is press fit into one of the 3D printed parts, which is then driven by the threaded rod.