I wonder what if there's a straightforward way to make facemasks by hand, or with tools that are generally available?

I'm imagining cutting apart a furnace filter and wrapping the fabric around a wire frame, or something like that. If someone were to develop a process that was simple and reliably repeatable and produced good quality effective masks, that could be a way for otherwise un-busy people to keep hospital staff supplied.

One issue I suppose is whether there are upstream bottlenecks, like not being able to get a reliable supply of the right kinds of filter material.