3D PRINT SETTINGS
For a watertight result, make sure your printer is well calibrated and lubricated.
Then, increase the wall line count to 3.
The wall thickness is 2.6mm, so that makes for about 6 wall lines with a 0.4mm nozzle.
That's plenty to make it watertight.

Resolution: 0.2~0.3 mm
Infill: gyroid ~20%
Build adhesion type: None
Supports: None