Summary

Note 1: I have not tried printing/testing the version 2!!
As far as I am aware, however, it should probably fit.
Note 2: This product will likely not work as well as intended when made purely out of rigid plastic. It is the positive for a mold (to be designed) so that this product can be made in silicone (see end of this text)

This is a custom made copy of the mask inner support frame found here: https://www.amazon.com/Homemade-Silicone-Comfortable-Breathing-Washable/dp/B08931ZQZC

This is a work in progress, as it is part of a project to make this product by hand in silicone. I am currently designing a mold to make this product, and will upload that mold when it is ready.

Some notes as a biomedical engineer:

1. This product will not compromise the integrity of your mask UNLESS it is bulky enough to prevent your mask from sealing (at least the soft seal that is achieved around the edges when using a surgical/cloth mask). You can test this by breathing out hard while holding your hand around the edges of the mask. If you feel air, then the mask's integrity is compromised. The "Old" version in the Thingiverse listing is a very close replica to the Amazon product (as far as I could tell), but I found that it was too bulky to allow the sides to seal. Because of this, I made version 2 which I have not yet printed/tested, but I think should work.
2. Being 3D printed, this product will likely not be able to be cleaned properly (silicone, as was originally intended, would be easier to clean). If you use this regularly, I would recommend leaving it somewhere to air out in your house for 3 days between uses (printing out 3/4 per person should make this easy to do) to ensure that you do not increase your possibility of spreading COVID-19.