Before you can start making your mask, you need to design it. Make a paper template of your mask on paper.
Draw around the template and on to the fabric. Draw two masks, remembering to flip the template, one with eyes and one without.
Cut the two mask sides out, leaving a small margin around the outline.
Cut slits through the eyes.
Stitch the excess fabric back around the eyes.
Cut out two squares of fabric in an alternate colour. These will go behind the eye slits so make sure to cut squares big enough.
Stitch the fabric squares in to the eye slits on the wrong side of the mask. Pin the top of the two mask sides together, wrong sides facing out. Cut a length of elastic, large enough to fit around your head.
Place the elastic on the inside of the two masks and pin in to place. Pin around the mask leaving one edge unpinned.
Sew around the pinned outline with a sewing machine, don't sew the unpinned side.
Fold inside out and stuff. Tuck the other end of the elastic inside the open edge and pin shut, folding the edges of the fabric under.
Sew the edge shut and you're all done. Time to shoot some bad guys.