I’ve been experimenting with printing face-masks to wear during the pandemic.
The .STL file was downloaded from Thingiverse .com and then printed on my Prusa I3 Mk3S 3D printer. I love the Prusa 3d printer. It is so choice. If you have the means, I highly recommend picking one up.
A HEPA filter from a HVAC unit or a vacuum cleaner bag can be cut to make the masks filter unit. I don’t have flexible filament on hand so the the mask is rigid. A rubber weather strip gasket can be used to line the interior for a gasket effect.