In this step, you will pin the pieces together along
the top and bottom edges of the mask.
For the top edge of the mask, measure 3/4" in from
both sewn sides, and place one pin where you measured on each side, then
pin between those pins.
For the bottom edge of the mask, also measure the
3/4" in from both sides, mark it with a pin, and pin between those pins,
leaving a 3" opening for turning your mask in a later step.
Note: It is important that you leave a 3/4" space on
both the top and bottom sides of the mask to create openings for elastic
channels once the mask is sewn.