This guy shows how to make a mask from blue shop towels. https://www.youtube.com/watch?v=mai-UqdNRi8

No sewing required. Materials are one shop towel, a paper clip, two rubber bands, some Scotch tape and staples. It took me 5 minutes to make my first one, subsequent ones will be faster. They fit and seal on the face quite well. I wore one outside for about an hour walking around and doing moderate exercise and did not feel winded or light headed so it seems I was getting enough breathing air thru the mask. There are a number of references on the web that say that the blue shop towel material has reasonably good filtration performance.