Its a mount for DualSense controller to work with regular phone mount.
I was inspired in a couple of different models and dualsense wall mounts so I made one myself connecting the phone mount with a controller.

It snaps, it prints pretty easy in PETG and most inportantly it works.
It uses M5 Bolt and Nut to connect with a phone holder altho if you have some washers you can use any smaller bolt and nut too.
Also it has cutouts for builtin mic and charging port.

It works with MODULAR MOUNTING SYSTEM and u can basically attach anything you wish.