Commercial single-use face masks include a pliable metal strip over the nose to create a better fit and seal at the top edge. In self-made reusable face masks (which are currently becoming very common) these are often absent - be it for lack of suitable materials, for easier production or for better washabilty.
In my own self-made cloth masks, I have been using a 3D printed part, that clips onto the top edge of the mask. It improves the fit on my face and reduces the air gap around my nose. The latter is especially important if you wear glasses (they tend to fog up when you breath out). Maybe it can work on your face, too!
I made two versions:
- nosebracket-widegap.stl - which leaves a slighly wider gap under the flexible clips, for masks that are too thick at the seam to fit the first model
To give you an idea of the width of the gap: my masks use four layers of (relatively thin) cloth. If your own mask is thinner, the nose bracket may still fit securely, if the edge has a slightly thicker seam.
I apologize for posting this a bit late, even though I have been already using my masks this way for weeks.
Mine are printed in PETG. They easily survive a wash at 60 °C or can be removed and cleaned/disinfected separately.