I took some scraps and made three 7" by 9" pieces from lightweight denim and the lining of an old curtain. Also two pieces of 7" of elastic band.
This is the lay-out. The elastic bands go between the pieces of denim.
An opening is left to pull the inside out. De elastic bands are double stitched.
The inside is pulled out. After a first ironing, the folds are ironed in. After ironing, the edges are stitched to keep the folds in. The mask is ready for use.
The mask feels a little bulky so with the next one I will skip the liner.
It is a somewhat loose fit but comfortable to wear for long periods. I don't post a picture of me wearing the mask. It will give me at least 10 years of hard labor.
