This is directly based on David Gentners design. Unfortunately his design had one of the two components slightly raised from the print bed resulting in spagetti. All I've done is altered the height of the object that holds the phone so that both components are at the same height (Z axis).

I printed scaled down to 70% though in hindsight I wished I'd scaled only X and Y leaving the Z height (which would have made for a much more stable base).

Printed in red PLA, 0.28mm layer height, 15% infill.