Four layers of satin mask (no cotton)
Satin is polyester - not to be confused with sateen (cotton) or silk (from an insect).
Here's six layers of satin that is from cut up sheets from Amazon. I've been using the same source for six months now for mask making. Wereas I'd coupled this satin with high-thread count cotton before, this is a mask that's not doing that.
Goal: mask that is high filtration and washable.
Constraint: a mask that doesn't require stiffeners / retainers / ribs to force the 3D cupping away from nostrils/lips.
This still RagMaskMax: https://cv-masks.github.io/ragmask-max.html. What's new is that steps 1, 2 & 3 are skipped. Also that step 6 is four layers of satin folded before sewing evenly spaced lines back and forth parallel to the fold lines. That's going to make the multi-layer mask have some stiffness - satin is very floaty and a single layer will quite easily pull into your nostrils on a breath in.
Mask above the old 750 thread count cotton and satin mask (one layer of each). Mask below the one I've just made - 4 layers of satin only: