I wanted to create a simple adapter/sled that fit around the Galaxy S21 FE phone inside the Gamesir X2 Pro Controller so that it looked nice and clean.
I printed the adapter vertically on it's side with a brim and organic supports. For the two buttons, you may have to sand them a bit depending on the tolerances of your printer, it is tricky to get them just the right size to seat well and not press down on the buttons all the time or be too loose.
I also printed a spacer on the back that is another part of another design from thingiverse: https://www.thingiverse.com/thing:5907243 and trimmed it down to 56mm in the slicer.
Depending on what filament you print with (I used overture matte black PLA) you should be able to flex it just enough to pop the phone in (mine did eventually crack at a layer line but mostly because I was doing so much testing). Something like ABS might be more problematic, but you could always slice the design in half and fit each side over the phone with a seam in the middle.
The author marked this model as their own original creation.