Face mask with slits

This mask has a slit on top for a piece of wire that can be folded to conform to the nose. It also has a pocket on the reverse side to insert a filter. This is a simplified version based on the one in this video.
This face mask is not as safe as an approved medical mask, but not everybody can get the more effective ones.

Cut a piece of tightly woven fabric, 7"x17". Cut a piece of bias binding 2"x7" and two pieces of binding 2"x36". The strips can be cut straight (as opposed to bias cut) if necessary.

Finish the short edges with a zig-zag stitch or a serger.

Fold the fabric in half and then fold center up to 3/8 inch below raw edges, and press. Bottom fold will be the top of the mask.

Press sides to center of short strip, then fold in half and press.

Line up folds and pin.

Top stitch the edge of the binding closest to the short edge of the fabric. Leave the other end loose for now. Fold the fabric in half with the right side facing in.

Sew 1 1/2 inches in from either end, 3/8 inch in from raw edge.

Turn inside out, open out seams, fold back open edges, and press.

Fold top and binding along fold lines and press.

Fold in half and place pins half an inch away from center on either side.

Pins should be one inch apart.

Top stitch along the edge up to the first pin. Backstitch and skip to the next pin, backstitch and topstitch to the end. There will be a gap in which a wire will be inserted to conform to the nose.

Turn the fabric over. With the bottom edge on the top, pinch up a 3/4 inch pleat slightly below the slit.

Fold upwards and pin in place.

Make similar pleats above and below, and pin.

Sew 1/4 inch along raw edges.

Fold short edge of long strip in 3/8 inch and press.

Fold long edges towards center and press.

Fold in half and press again. Turn over and press, using steam or spray bottle. This will help keep the strip in place for the next step.

Fold strip in half and align mask with center.

Open the binding and tuck the mask up to the fold.

Pin in place. Top stitch the entire strip from start to end. Turn the mask over and make sure the strip was stitched down on the back. If not, stitch the back part of the strip.