I saw https://www.thingiverse.com/thing:1068484/ by kieranjones.
It was functional and nice but too small for my mobile.
I decided to remix it, redrawing in Freecad, putting 4mm constant thickness and making the holder a bit deeper (12mm) and wider (60mm). I attach here both .STL and Freecad source. Enjoy and modify if you need it !

Artillery Genius

No

No

200

20

layer: 0,16
speed:40
temp:205
bed:65