Mask Kit -Potluck, Anything Goes - fabrics are stores choice
Kits include 2 coordinating pieces 1/2 yard each of 100% cotton, quilt shop quality
1/2 yard of non-woven fusible interfacing
5 yards of elastic.
Will make 6-8 masks, depending on the pattern used.
Kits sold as shown. No Substitutions.
Link to a pattern that is easy to make:
https://www.patricklose.com/face-mask-tutorial.htm
Other ways we have finished masks using this pattern:
1) Cut a piece of elastic 30"-32" long and run thru the casing as the ribbon in the above pattern. Adjust to fit your head and stitch ends together.

2) Cut 2 pieces of elastic about 6" long. Insert the ends of 1 piece into the casing opening on one side and stitch the opening closed. Repeat with the other piece on the other end.
You might also need to add a small pleat in the top fabric on each end to make the mask fit your face better. I added about a 3/8"-1/2" tuck in the one below.