Update 10/27/2020:

Added an additional STL for mask bracket "bumpers". My biggest issue with the original design is that the corners of the bracket tend to dig into the face a little. This new component is a retrofit solution that remedies this issue by rounding off the sharp corners. The bumpers should ideally be printed in TPU but will still improve comfort if printed in a rigid filament. They simply slide into place on the corners of the bracket. To ensure they don't fall off, I suggest putting a small dab of superglue on the corners first.

This is a remix of the design by 1sPiRe. It inherits all of the great qualities of the original design (comfortable, quick and easy print) and builds on it with the addition of a new method of attachment and adjustment. My contribution is the design of a sliding clasp system. This clasp inserts into the slot that runs down the centre of the mask spacer. To attach to the mask, first make a small crease in the fabric. For multi-layered masks, just crease the innermost layer. Then flex the mask spacer to spread apart the teeth on the clasp. The teeth will bite into the fabric and keep the spacer attached to the mask. The mask spacer can then be slid up and down, with the clasp sliding in the slot, to achieve the ideal positioning. What's great about this new system of attachment is that it doesn't require the mask be pleated, like the hook system does, and it enables the adjustment of the spacer positioning.

For maximal comfort and durability, I recommend printing the first layer of the spacer in TPU and the subsequent layers in PETG (use M600 filament change g-code).

The clasps can be printed with a filament printer but if you have a resin printer at your disposal, they'd print even better on that.

It wasn't specified in the original Thing but this goes under your nose (not on it) and around your mouth.