Starting from one corner, sew around the curved part of the mask, leaving a 1/4" (6 mm) gap from the edge, just like you did before.

Make sure to keep the elastic bands out of the way. This can be a little bit tricky, but isn't too hard.

Be careful when you get to the nose bridge insert. Make sure that it stays pushed up against the seam. The presser foot will sit at an angle while you sew along the insert.

Remove pins as you proceed, if necessary.