According to this US CDC site, 3M is the sole NIOSH manufacturer of N95 filters: https://www.cdc.gov/niosh/npptl/topics/respirators/disp_part/n95list1.html htt

According to this US CDC site, 3M is the sole NIOSH manufacturer of N95 filters: https://www.cdc.gov/niosh/npptl/topics/respirators/disp_part/n95list1.html https://www.cdc.gov/niosh/npptl/topics/respirators/disp_part... As an Earth scientist, I could imagine a mineral based replacement for the filtering part -- e.g. something like a zeolite -- but the lack of mechanical flexibility and the risk of silicosis are two serious problems with that right off the top of my head. How about 3D printing of filters? Can N-95 -- 95% of particles greater than 0.3 microns -- be achieved? Edited to add: It appears somebody is doing this for liquid filtration: https://liquico.com/products/ https://liquico.com/products/