Print the base and the ball joint, add an M4 brass threaded insert in the ball joint with a soldering iron, and screw them together with an M4x10 flat head screw. Clip your phone holder on the ball, and place the assembly on your numpad.
I've printed the base from ABS without any support. Support might be necessary if your printer not handles well larger bridges.
The ball I've printed from Formlabs ESD Resin because that's what I had in black. It might work on FDM ABS as wll, but I did not tried!
The author marked this model as their own original creation.