The hardest part of the build is making a worm drive or something similar to it. After some testing I decided to make a grooves in worm wheel using two-part epoxy repair putty. As a worm and its shaft I used nylon threaded rod.
The final product was in use only few times, enough that I determined its pointing accuracy and smoothness of movement. Accuracy of pointing to a desired object was within 0.5°, enough that the object was visible in 25mm ocular with ~1° of FOV. Smoothness of movement when looking through ocular, while the scope was moving, event at microstepping was not very good. The jerky motion between motor steps was visible. For this reason I never tried to upgrade software for object tracking.