Better phone stand

Phone stand with a set of features that i couldn't find in other designs:
- has stiffening ribs so it doesn't wobble when you touch the screen
- bracket has a gap to insert a phone with a cable without taking it out
- bracket doesn't obstruct android navigation bar buttons
- does print perfectly without supports

Model is fully parametrized, see f3m file if you want to change anything.

I've added two versions: with bracket size of 9 mm (default) and 11 (for thicker phones).

There's also "steep" version of design which has steeper overhangs (55 deg), but i like the looks more. Default overhangs are 45 deg, which should be manageable for most of 3d printers.

STEP files are recommended as they have higher geometry precision.

Designed & tested for PLA, default Bambu lab settings, brim and supports disabled.