Hello everybody,
here are some (interesting) links regarding 3D print face mask:

https://www.ciirc.cvut.cz/covid-2/
https://www.prusaprinters.org/prints/25626-modular-face-mask
https://www.prusaprinters.org/prints/26938-modular-face-mask-more-hepa-filters-upgrade
https://www.thingiverse.com/search?q=breathing+mask&dwh=505e704c4d091d0&type=things&sort=relevant
https://grabcad.com/library?page=1&time=all_time&sort=recent&query=filter%20face%20mask

Peace of mind
Mik