Phone holder allows for fine control of tilt.  Probably overkill for some uses, but think this might be useful for video chat or work conferences where you want to get the camera angle just right. 

Link to adjustment demo GIF:  https://drive.google.com/file/d/1McKVSAtGteZpH0tnaasFR7kEc2QWJiKA/view?usp=sharing

Updated version printed in white added to pictures; file: “phone holder latest”, this is the version I most recommend. –  Another update, phone holder_clean has no text on top side for cleaner print.

Print vertically on side with adjustment knob away from build plate.  Example printed with .2mm layer, 15% infill.  Recommend 6 mm brim ears with detection radius >10mm so gears don't get ears if using SuperSlicer.  For PrusaSlicer you can add helper disks, just avoid overlaying gear teeth.  How to for helper disks : 

 A little PTFE lube helps it run smoother

 Link to Solid Works Gear Generator app for your own designs with gears.

NEW Phone Stand Model for your  consideration: 

https://www.printables.com/model/1258296-phone-or-tablet-stand-adjustable

The new model is also a ridiculously over engineered phone stand that fixes the one issue with this model, which is that with enough off center weight it will back drive and not hold position. The new model holds very firm in set position.