Speaking of n95 masks, my wife has some shop towels coming tomorrow that have been tested for pore size. They are supposed to be better than n95! She has some patterns for cloth masks with a pocket for one of these membrane filters. I think she's going to whip a few up for friends and family.

One very important factor in getting a really good mask is the fit around the edges: There was a video on Youtube where a nurse was testing some homemade mask designs. One was very good, but she had to tape it under the chin. A good mask is useless if it leaks around the edges.