Cut the thin portion of the print to properly size the height of the square to your pocket. You may also want to round the corners. Use white filament. 

Print Settings

Printer Brand:

Prusa

Printer: 

I3 MK3S

Rafts:

No

Supports: 

No

Resolution:

0.2mm

Infill: 

12%

Filament: Prusa PLA White