Changeable filter

thingiverse

I printed out several of the original mask designs for my family and I'm grateful to Chris for sharing them online. My wife and daughter weren't too fond of the post-apocalyptic look, but I enjoyed it and decided to add some personal touches. However, I encountered a bit of a challenge when trying to replace the filters - they just wouldn't come out easily. So, I came up with a solution: I designed a removable section that can be attached using hot glue and creates an air-tight seal. The filters I'm using are a combination of MERV 12, 14, or 15 ratings. The design allows for at least three layers to be pressed into place within the recess created by the mating section. My setup consists of a single layer of thin cotton fabric as the bottom layer closest to my face, followed by a layer of MERV 12, and then two layers of MERV 14. I did try using three layers of MERV 14, but it was too stiff and made breathing out difficult. I made one modification to the mask itself: I removed some of the nose bridge area to improve the fit on my test subjects. To make the mask more comfortable, I lined it with 1/32-inch thick closed-cell adhesive-backed neoprene rubber. If there were still gaps, I used 1/16-inch thick material to fill them in. I tried to position the neoprene so it could be folded over the edge for a better seal. These modifications are specifically designed for the narrow form of the mask, but they might be useful for others as well.