We’ve made a couple hundred masks here in Denver for medical personnel, essential workers, and everyone else who wanted them. Our favorite pattern so far is
https://thecraftyquilter.com/2020/03/versatile-face-mask-pattern-and-tutorial/
we also bought Honeywell ac filters, chopped the metal off and put them in the masks. Works great. They’re made of the same crap the N95 masks are made of, or so I read. Chop the filter 1/2 inch smaller all around than the mask pattern For fitting. For straps we couldn’t get elastic at the time, so we used 550 cord, and ordered ‘plastic paracord lockers’ off the internet.