What you need:
For water tight result recommend settings bellow and also read these articles
Layer height: 0.15 - 0.2mm
Temperature (PLA): 220 °C (upper limit of temperature recommended by the manufacturer)
Perimeters: 3 - 4
Brim: yes
Layer height: 0.3mm
Brim: yes
Pull string through the loop on the side with the longer overhang, all the way down and wrap up. And finish at the loop on the other side.
The author hasn't provided the model origin yet.