Additional valve designs

[stephen304]

This is essentially an open invitation to anyone who wants to make new one way valve designs. Currently the only design in the repo is a more-or-less fully printed design that relies on having a smooth build surface and works best with a well calibrated first layer and flexible build plate (eg. smooth pei spring steel). We should also have valve designs that use more off-the-shelf parts to allow a wider number of makers to produce working one way valves.

The one way valve should be designed around the 40mm nato male reference model to ensure compatibility with all of the masks in the repo. The nato thread reference length and outer geometry should not be modified, however the design of the tightening knob on the end is up to the designer.

Potential one way valve ideas include:

• Using a circle cut from a balloon to make the flap
• Using a flat door that seals on an o-ring embedded in the surface
• A valve that has the same geometry as commercial mask valves, so that replacement diaphragms can be purchased in bulk and installed
• Using a commonly available spring or rubber band to create the mechanism for the valve

Potentially draw inspiration from:

• https://www.thingiverse.com/thing:4462940 (center-retained tpu circle based)
• https://www.thingiverse.com/thing:4336351 (molded silicone/caulking? flap on compliant tensioner)
• https://www.thingiverse.com/thing:4239168 (center-retained balloon cutout based)