Melt-blown fabric is not a requirement. It's just what we have been using. It is good enough for the job, and it is really cheap if you already have the machine

Melt-blown fabric is not a requirement. It's just what we have been using. It is good enough for the job, and it is really cheap if you already have the machines. There are types of aerogel that are flexible. When created with embedded fiber for strength, it works great. Setting up the equipment would not be too difficult. The filtration is far better than with melt-blown fabric. We have many more options if we don't insist on flexible fabric. Gas masks commonly use canister filters. With that style we can use a rigid filter. It could be sintered glass, sintered ceramic, sintered metal, metal foam, aerographene, aerographite, graphene foam, or diatomaceous earth. We could even go electronic, with a UV light. Materials with high air flow resistance are usable if we add a blower. There is a doctor in China doing this in a makeshift way, with a HEPA filter on his hip and a plastic bag over his head. An advantage is that it protects the eyes, which are an infection path for the virus. Eye protection needs air flow to prevent fogging and because eyes actually require air.