  Motorized rotation mounts and stages are versatile instruments that introduce
computer control to optical systems, enabling automation and scanning actions.
They can be used for intensity control and position adjustments, etc. However,
these rotation mounts come with a hefty price tag, and this limits their use.
This work shows how to build two different types of motorized rotation mounts
for 1" optics, using a 3D printer and off-the-shelf components. The first is
intended for reflective elements, like mirrors and gratings, and the second for
transmissive elements, like polarizers and retarders. We evaluate and compare
their performance to commercial systems based on velocity, resolution,
accuracy, backlash, and axis wobble. Also, we investigate the angular stability
using Allan variance analysis. The results show that our mounts perform similar
to systems costing more than 2000 Euro, while also being quick to build and
costing less than 200 Euro. As a proof of concept, we show how to control
lasers used in an optical tweezers and Raman spectroscopy setup. When used for
this, the 3D printed motorized rotational mounts provide intensity control with
a resolution of $0.03$ percentage points or better.
