Montana Mask Utah Edit

thingiverse

This redesign of the Montana Mask was created by Dr. Dusty Richardson, Dr. Specer Zaugg, and Colton Zaugg at makethemasks.com. It solves a major problem - inserting a filter into a square hole can damage it. To use this design, simply place a 3 inch diameter filter over the hole, secure it with the filter retention body, and screw on the cap for a tight seal. Edit: V1.2 maintains the same overall design but increases the breathing hole to 5.2cm in diameter, boosting the filter surface area by 70%. Edit: V1.3 ups the ante again by enlarging the breathing hole to 6.2cm for smoother air flow and increasing the strap hole size. Bumps on the mask body prevent the filter retention body from rotating when tightening the screw. Different versions have incompatible parts, so use them separately. Thanks to hazeldazel and PonderingWalnut on Reddit for verifying v1.3.