This small jig helps to center the glass protector over the Garmin Forerunner 165 display.

These are the protectors I use, but I think they must all be around the same diameter (37.4 mm).
This design is extremely tight. Make sure your print profile is well calibrated. Even a 0.05 mm variance in overextrusion can render it useless, so please let me know if it's too tight for your protector and I will try to upload a less restrictive version.

This is how I use it:

1. Thoroughly clean the display. I used alcohol, but this might not be the best approach. Make sure that the sides are completely clean and that there is no dirt between the display and the bezel.
2. Clip the applicator over the bezel.
3. Remove any dust that might have settled on the display.
4. Remove the adhesive film from the screen protector and allow it to fall through the applicator tool.
5. Once you are happy with the position, lightly press one of the sides and the screen protector will adhere without bubbles.
6. Thoroughly press the screen protector in place. I used a microfibre cloth to help my fingers slide over it easily. You can still make slight movements at this stage.
7. If possible, heat it up a little with a heat gun and keep pressing while it cools.