I have looked at several ways of making these masks. While they each net pretty much the same product, this seems to me the easiest way to make many in short order.
|Cut 2 rectangles, 6" x 9" and press short ends to the wrong side about 1/4"|
|Stitch both long sides. Turn inside out and press.|
|Cut 4 - 6" lengths of 1/4" elastic. Insert 1 end of 1 piece at the top of the side opening and pin in place.|
|Top stitch through all layers until about 1" from other end.|
|Now make 3 pleats by making about 1/4" folds and top stitch to hold. Stick the other end of the elastic in the 1" remaining opening and top stitch to finish off that side. Repeat for other side.|