Grab/Release Phone Stand

This design is an attempt to improve the one of Arron_mollet22 : https://www.thingiverse.com/thing:3681512

I have started from scratch so pieces ar not compatible with the one from the link above.

List of upgrades :
- Printed screws that maintain stand feet, back arm and holder together have been replaced by M4x16mm screws (and M4 nuts)
- I have removed the utilization of the metal spring by improve gears like in this design: https://www.thingiverse.com/thing:4674815
- Plastic screws that maintain front and back case part together have been modified to make it easier to screw.
- Some space between all move parts have been added in order to make it easier to slide.

This design have been tested with a Samsung galaxy S9