Here I designed a phone stand in fusion 360.
I used my own phone(samsung s20) for reference.
My phone does have a case protecting it.
I made it so the usb charger can pass through the hole in the file so it also servers as a charging port.
I made it angled at 60 degrees.
This is one of my first times using a CAD software since I've only recently learned about this in school.(I'm 15yrs)
For infill patern I used lines but I'm sure any other patern wil work.
Just make sure the infill density isn't too low, I recomend around 40%
I printed it on its side and sure enough there was some stringing.
The lines sticked a little to well to the printed causing some layers to be missing on the print.
As far as suport goes, please make sure you don't under-estimate youre printers abilitys and put the support to the max. Other wise it's going to be a real pain in the a$$ to remove them all.

I printed this on a BQ Witbox 2 at school.
Bed leveling took some time but once the print started it was fine.

You can download 2 files: stand v2 is a little narrow for the phone to slide in.
Mine nearly fitted but my teacher had a slimmer phone so i gave the v2 to him.

I added another stand but with a little more clearance; phone stand v3 has the most clearence.

please feel free to give some feedback on how I can improve.

Print Settings

Printer brand:

BQ

Printer:

BQ Witbox 2

Rafts:

No

Supports:

Yes

Infill:

40%

Filament brand:

esun

Filament color:

green

Filament material:

pla+

Notes:

don't go extreme on the supports.
Be reasonable to estimate how much you would need.