1. I found an old bikini top. Keep one cup on ribcage string, discard other cup. Cut off neck string and tie it to rib string to increase length. Wear upside down - point goes over chin, ribcage string goes over nose and ears, tie in back. Maybe not the best material because it is a poly blend, but it has a lining sewn in and it is easy to cut a slit and add a filter. Small, but super easy.
2. I found some old cloth napkins, the kind you might have to iron, cotton linen. I think this material is very good and can be used for the simple Korean no-sew scarf mask.
Thank you for the thread.