I'll throw this idea out there for anyone that wants to run with it: one of the problems we have is disposable masks that don't fit properly, particularly around the nose and cheeks as they are to some extent stretched over the high points of the face. This is particularly important for health care providers obviously.
I suggest the solution is 3D scanning of the faces of these workers and 3D printing of mask holders to fit the face of each worker precisely.
The holders or frames can be configured for whatever disposable mask or screw-on element is available or suitable.
If paper masks are used as the "element" , a recess in the holder or frame can be created into which the paper mask is placed and either secured with a removable adhesive or a 3D printed ring or "frame" which will make a tight seal against the main holder or "frame". Some kind of snap or clip attachment being advisable obviously, perhaps with a compressible lining on one or both sides of the paper mask to ensure a good seal. Perhaps some off-the-shelf sealing strip could be used for that?
For the best seal around the face, a convex edge which can be covered with medical tape(?) to keep the plastic of the 3D printed frame off the skin may be best, or a flat edge to which some disposable adhesive and compressible sealing "tape" can be attached?
3D scanning and printing technology is common and easily transportable and pretty quick these days.
So there it is. Maybe it's out there already, I haven't looked.