This mask has been reviewed in a clinical setting by the Billings Clinic. The mold you see here has a far more optimized remix at https://3dprint.nih.gov/discover/3dpx-013921

The remix at https://3dprint.nih.gov/discover/3dpx-013921 deprecates this design by providing a way to print a shell to cast a better mold than the one you could print here.

I'm not a PPE manufacturing specialist.  I'm not a lawyer.  I'm just a computer nerd who's trying to save the lives of people I admire.

This is a mold to rapidly produce Dr. Dusty Richardson's mask design.  https://www.cnn.com/2020/03/23/us/coronavirus-3d-printed-medical-supplies-trnd/index.html.  There is no way we are going to print enough masks in time on machines designed for prototyping.  Additionally, there's a lot more that can go wrong in a 3D print versus a cast(delamination is the big one).  I also worry about surface porocity. 

This mold can be printed and then masks can be made in any garage and requires no 3D printer after the mold is made.  By using resin to decrease surface porosity, HCW will be able to scrub the mask frame with bleach and add a fresh filter.  This will introduce the idea of a semi reusable surgical mask.  Not to replace an N95 in any situation beyond an emergency shortage.  The mask frame is designed to allow 2inch square filters to take the place of a full surgical mask.  This mask clearly makes a more reasonable attempt at forming a seal around the nose and mouth when compared to a surgical mask.  Filters are made by High Tech Filters in Billings. http://billingsclinic.com/foundation.  The Billings hospital will accept them as replacements for surgical masks, but who knows what hospitals will be forced do if they run out of N95 masks before heavy industry can ship to them.  The general public does not have the apropriate knowledge and equipment to manufacture and QC N95 masks, but we should be able to collectively come up with a reasonable contingency for a shortage of supplies .  https://www.thingiverse.com/thing:4249376 

I recommend including the documentation found at https://www.makethemasks.com/ and adding two warnings similar to the following: 

1. If the mask smells like curing plastic, do not use.  Air mask out and use after no fumes are detected.
2. If you get a headache while wearing this mask, replace mask immediately with a mask other than a resin casted mask.  Temporarily seek fresh air.

Use the following mold making materials to create a very safe version of this cast!  Thanks Smooth On! :)

• Ecoflex 00-35 to create molds
• TASK 8 to cast masks (to allow the mask to be cleaned in an autoclave!)
• Smooth-cast Semi-rigit 61D Casting resin to cast masks that wont handle an autoclave (some flexibility for an improved face seal, but still very rigid for the filtration insert)

https://www.youtube.com/watch?v=UihNGI5Y1t0

This particular virus has been neutralized on the montana mask(ABS FDM) completely with bleach(so an autoclave is possibly unneccesary).  

It may be non-critical, but wise to include a gasket with this mask.  I can hold a 10 second suction with nothing other than the 61D casting resin... but everyone's face is a little different.  Consider including some window sealing gaskets as semi disposable gaskets, or make some cleanable/reusable silicone gaskets as in the video.

From Smooth On:

Smooth-On produced this video in response to people asking for a workable (not perfect) materials solution to the problem of respirator shortages plaguing many parts of the world during the COVID-19 crisis. Before responding to viewer assertions that the HEPA vacuum cleaner filter bag that we featured in our video contains fiber glass making the design unsafe, we wanted to investigate to get the facts to the extent that they are available. Kevin Egan, Head of North American Sales at TTI (parent company of Hoover and Oreck vacuum located in Ft. Lauderdale, FL) states that “I’ve checked with our product team and can confirm our bags do not contain fiberglass”. We were directed to a YouTube video made by Josh from Vacuums R Us in Arvada, Colorado to separate myth from fact based on his years of experience in the trade. Josh is very clear that HEPA vacuum cleaner bags have never been made of fiberglass. https://www.youtube.com/watch?v=vmYt_wtaLCk&t=61s . We have spoken with several hospitals that maintain dedicated medical simulation device fabrication departments. Health care workers continue using HEPA vacuum cleaner filter bags to make their own DIY respirators without any reported incidence of adverse health effects. An RN that works in the Med Sim fabrication lab of one facility commented that, “at the moment, HEPA vacuum bag filters are our only option”. Our Conclusion; N95 filtration masks are optimal in fighting the COVID-19 virus. Due to the severe shortage of these masks, however, people are forced to improvise and do what they can to protect themselves, their patients and their loved ones. While we respect the opinions of others, Smooth-On is satisfied that we have done our due diligence in researching this matter. We were not able to find a single HEPA vacuum cleaner filter bag made of fiberglass anywhere. The majority are made of spun polypropylene fibers. A small percentage are made using a combination of cotton and cellulose. We also confirmed that Furnace/HVAC filters do contain fiberglass and should not be used to make PPE devices. In producing this video, we followed the lead of local health care professionals in using what they consider to be acceptable filtration in the face of the N95 mask shortage. Given a choice between no filtration and using a HEPA vacuum cleaner bag filter, we think most people would opt for the latter.

From Flowmark/Hightech filter's website: 
The 3D printed mask and filter information is intended to assist the general public during the current a global pandemic related to COVID-19 and the related nationwide shortage of personal protective equipment.  Please be aware that this mask design and filter is not intended to replace standard protective equipment such as N-95 masks or surgical masks when that equipment is available.  The use of these 3D printed masks and/or their media (filter) has not been fully tested and has not been approved by federal or state authorities.  Billings Clinic, Marlin D. Richardson, M.D., Spencer Zaugg, DDS, Colton Zaugg, and Flowmark/HighTech make no representations or guarantees regarding the safety, efficacy, or appropriate use of these masks or filters in any particular situation.  Use of this information for any purpose is at the maker’s and user’s own risk. 

https://www.flowmarkhightech.com/