This .scad can generate a back-of-the-head face mask holder of any length, width, with any number of "teeth" of any size (at any angle!). It even lets you customize it with a corporate logo, custom emoji, or whatever text you like. It can even generate models for multi-material printing (to get that crisp look like the one in the photo)!
Included are a number of ear saver STLs (all generated using the .scad):
Why I made this: My mother-in-law made me an awesome face mask but the elastics are slightly too short and it uses elastic bands that are much thicker/wider than standard face mask elastics... So none of the existing models actually worked to hold it on!
I figure I can't be the only person with these sorts of problems so I made a parametric face mask holder generator that can be used to make one with whatever parameters you need.
EDIT 20200410: Made loads of improvements:
Just print it flat (I used 0.2mm layer height but smaller or larger layer heights will probably be fine too). I printed mine in PETG but it's thin enough that it should work fine with basically any filament (e.g. PLA).
For MULTI-MATERIAL prints (e.g. you have the MMU2) just add the *_legend.stl as a part to the main .stl
For COLOR/FILAMENT CHANGE prints (e.g. M600) use the *_outset_legend.stl version and set the filament change at 1mm.
The author hasn't provided the model origin yet.