1. Choose and cut fabric
A Cambridge University study shows that antimicrobial pillowcases, cotton-blend T-shirts, and dish towels filter a higher percentage of particles, but any lightweight washable fabric will give some level of protection. The thinner your fabric, the easier your sewing.
It's best to choose different types of fabric so you can tell inside from out when putting on the mask. We found some leftover material from a Space Girl party dress (that was a wild party!) and some plain white muslin. Lay your two fabrics over each other and cut out a 9-1/2 in. square. You can also make scented sachets from fabric—here's how.
2. Edgestitch No. 1
With your two square pieces of cloth layered over each other, fold over two parallel edges about 3/8 inch and iron them flat. Many plans we looked at called for hand pinning folds and pleats for edge stitching, but if you're not a seasoned seamstress you'll find ironing far easier.
Once your edges are folded over, stitch those same two edges. On our mask-making night, my partner assembled a half-a-dozen masks on a sewing machine in the time it took me to stitch one by hand.
While I'm much better with a hammer or power tool in hand, I found the quiet task of hand stitching relaxing, even if my results paled in comparison to those from the sewing machine. A sewing machine is not necessary for clothing repairs—here are 9 random items you can use instead.
3. Create pleats
A pleated mask will provide the best universal fit. Keeping the stitched edges top and bottom, iron in three pleats, leaving a total width of about three inches.
How to Make a DIY Face Mask, Source:https://www.rd.com/home/how-to-make-a-diy-face-mask/