I add the magnet into the holder。
if you don't have magnet,
you can choose choose the no magnet here
https://www.prusaprinters.org/prints/30199-fold-phone-stand-holder
Here only STL file.
If you printing this.
Need to add the pause print into gcode.
You can check here.
https://forum.prusaprinters.org/forum/original-prusa-i3-mk2-s-others-archive/pause-print-in-gcode/#post-130384
The author remixed this model.