https://www.youtube.com/watch?v=N3eolKneE0Q

This will allow people to print master molds that allow anyone to cast molds which allow anyone to cast masks from each mold.  I designed this so you will be able to produce N-1 masks per casting(about 8-45 min depending on whether you're using Task 8  or Smoothcast 61D casting resin) where N=number of molds.  If one were to cast 10 molds from one of these prints, she would be able to cast 9 masks per hour.  Expect to get around 70 castings per mold if you use Moldstar 15 to make your molds and smooth on 61D casting resin.  We need a good logistics chain to QC development and manufacturing.  I recommend channeling your equipment through a makerspace that can act as a Point Of Contact between the hospital PO and civilians willing to make masks.  Use plastic casting resin that wont continue to off-gas several days after production(talk with Smooth-On for more details).  I use Semi-Rigid 61D for a slight flex(to fit the face), but not so much flex that the filter isn't tight.

While I have suffered no noticable effects from 10 hour useages after 4 days and a head engineer is impressed with this project, Smooth-On cannot recommend using 61D(or any other smooth cast product) without also creating a skin safe silicone face gasket out of a skin safe silicone like EcoFlex 00-30.   https://www.smooth-on.com/tutorials/making-diy-hepa-respirator/ 

I have to gush for just a second:

Smooth-On is a high integrity company that treats both their customers and employees well.  You can buy from them at their Smooth-On Store, or Reynolds Advanced Materials(if you want to save on shipping).  I've gone down the route of mixing my own silicone.  That's pain and agony.  Smooth-on's products are just mind blowing.  It is *very* hard to screw up when using this product.  My molds have lasted well over 50 casts now and they're doing pretty well.  I hit them with Ease release 200 every three casts or so(when I feel like the silicone has lost some of its lubey feel). I store the molds in a garbage bag all nested together.  There is very little air touching the nested molds.