Place one sheet of paper with its right side facing up -- this is "Paper A." Create a center margin on this paper by measuring 1 inch from its left edge with your ruler. Draw a light pencil line from the top to the bottom of the paper. The line will be the center of your mask and the margin will be the overlap for gluing the sides together.
Fold Paper A along the line you just drew. Set it aside.
Draw half of your mask on the wrong side of the second piece of colored paper -- called Paper B -- beginning at the left edge of the paper. Draw half of the nose and half of the mouth, starting at the paper’s edge. Draw one eye starting 1/4-inch from the edge. Cut out all shapes as needed.
Place Paper B on top of Paper A with the right sides facing. Align the left side of Paper B to the outside edge of the fold of Paper A. Using Paper B as a stencil, run your pencil through the cut holes and along the outside shape of your half-mask to put the identical shapes onto Paper A below.
Cut out all of the shapes on Paper A, even through the folded central flap.
Position Paper A with its right-side up and the fold straightened out. Run your glue stick along the flap. Align carefully the two sides of the mask along the crease, pressing them together along the flap.
Outline all shapes with your marker and decorate as you wish.