Cut two squares 8.5" x 10"
Cut two elastic straps 6" long
Fold each square in half on the long edge and press that middle fold; then fold the two half sides inward up to the first fold and press. There will be three pressed folds in the direction of the longest edge sectioning the piece into quarters.
Lay out flat and bring the two outer folds up to meet each other on the center fold.
Attach the elastic to the top and bottom of the short edge about 1/2" from the corner and sew/tack in place with the strap looped inward on the face of the mask.
Place the two pieces together with right sides facing....sew a 3/8" seam leaving 3" open for turning...trim the corners for turning then turn the mask right side out.
Push out and press the seams then sew a 3/16" top stitch around to finish.