These models are meant to be printed in TPU with 3 perimeters and 4-5 top / bottom layers.
If the Flex Material is too soft they may not stay open upright, but it works with the Overture TPU I have. Also if it gets too warm they may become flop down instead.
The "OD" in the filename - the diameter of the tube the ring fits on
OD62 - fits a riflescope with 56 Lens diameter
OD50 - fits a riflescope with 42 Lens diameter
Other diameters will follow.
The author marked this model as their own original creation.