Introduction: N95 Mask Alternative?

After hearing on the news for weeks about the lack of PPE (in particular the N95 mask), like many Americans I became concerned for our health care workers. Then, one week ago today, I call to 3d print them. So I went searching to see if there was anything available. Now, if any of you have done a search, you have probably come up to the hack the pandemic site: The mask looks very cool right? Antimicrobial plastic, fantastic! And releasing a patent into the public domain, how noble!! But...just a minute...I wasn't born yesterday...

The mask may look cool, but hasn't been tested? And look at the assembly/fitting instructions. Is this really something that a health care worker can be expected to do? Does it sound comfortable to wear? At the thickness printed, this type of plastic is hard; does that sound comfortable to wear all shift? What about being antimicrobial? It's "scientifically validated", right? But hast it been tested and certified by the CDC? NIH? FDA? Sadly, none of this info was there. And the patent? Well, for just $300, anyone can pre-file a patent and use "patent-pending". They can just not file the patent (abandoning), and say they are open-sourcing it. Then, do a press release. And publicity, along with orders for filament, come pouring in.

This is snake oil. The mask design is not correct for most uses. It will probably never work. And it is highly doubtful that any home printing and assembly (using their methods) would be more effective than a bandana. Seriously, print one out and hold it up to a bright light. (I did; I set up a print ~ 2.5 hours - while I continued to search for designs) See all those pin-pricks of light? That's a problem?

[Wondering why the rant about this? All will become clear...]

I found, instead, a design for a frame on thingiverse. Aside from using an unknown paper filter material and clips to hold the paper (or other material) on, it looked promising. So I printed it, on my smaller printer, in just 20 minutes. It snapped together perfectly, when pressed against my face seemed to conform to it rather easily. This has real potential, I thought. Now on to the covering material; I could (and did) research this, but professional advice would be helpful. And will this meet the needs of the health care workers?

Since I live close to a medical center, I called a friend who's wife works at an area hospital in administration. I explained the situation and asked who (department-wise) I should ask for at the center in order to discuss the possibility of helping with the mask shortage. Wonderful idea, Infectious Disease Department, let her know how it goes. So I called, left a message, explained that I had a possible design to 3d print. That I'd like to show it to them, ask for feedback on fit ( I can redesign it if some tweaks are needed), and looking for help on material selection (for the covering). 48 hours and no reply. Then my wife reminded me that we knew some who worked at the medical center. So I called him and he was very excited. He said he'd tell his manager the next morning and they'd get back to me. Another day and nothing but silence. When I updated my hospital admin friend, she tried to find another for me to help. She suggested contacting Mass General Partnership on covid-19: So I sent them an email detailing what I'd found (including link to original design on thingiverse), questions I had on materials, etc. By then I had researched materials, picked something that I thought might work, made a mask, although it was just pinned together at the time. So attached to the email I sent were photos of the unscrambled pieces, assembled frame, and covered frame. And their response? Please watch this town hall (which I had already done) and sign up to join their working group to discuss these issues where I'd be assigned to one of the sub-committees. I have no desire (or ability) to sit around and discuss these issues. Yes or no, does it work? Bureaucracy...

I suspect that many hospitals have been inundated by people offering to print the design from hack the pandemic, due to the media attention it received. And so they may ignoring valid offers of help, not recognizing them as such - throwing the wheat away with the chaff, if you will. Thus my rant above. Plus my general loathing for a company that would try to exploit a crisis for financial gain.

[Almost done with preface, patience.]

But the yesterday, I heard that the governor of NY, who had for weeks been warning of the dire consequences of the lack of PPE, in particular N95 masks, suddenly says they have an adequate supply. What???!!! But their still on the news complaining, in your own state. I give up. I believe no one.

Previously, I'd been careful not post anything to cause a run mask making supplies. Or substitute supplies, as you'll see below. But after that announcement, why? I decided to release this into the wild instead of working with the hospitals and the states. Let them fend for themselves. Or let someone else try to help them.


Plastic pieces (see

non-woven cover material (6"x9" felt square will produce one mask - use soft felt only!)

1/4" elastic or 12" rubber band for trash cans (0.20" wide)



Step 1: ​ Choosing a Covering Material

If you look into the specs and the history of the N95 mask you will see that it calls for a "non-woven" material. Well, what's a woven material in the first place? Virtually all of the fabrics you are familiar with. View the a bright light through a material like a tee-shirt. See those bright spots as you move it around? Those are considered "direct vectors". An air-borne pathogen - which covid-19 might be - can easily travel through this. Respiratory droplets probably won't, but your eyes are still exposed to them. A non-woven, such as felted, material has virtually no direct vectors, causing the air flow to twist and turn as it passes through. Any microbe, being more massive than air molecules, is forced to the outside on each and every turn. This results in higher likelihood of cllision with - and capture by - the material. Originally, they used felted wool. Now, spun polypropolene fibers. I found a soft felt "square" (6"x9") made of PET that should work well, but have not gotten any guidance on it, as documented above available at JoAnn. There are others, including wool/acrylic blends that should work. For those concerned about breathing in the fibers of the felt, there is a simple solution: a layer of cotton material under the felt. Cut both out and assemble making sure the cotton is on the inside (closest to the mouth). While the woven cotton fabric will do nothing do stop pathogens, it will prevent any larger fibers from getting through.

Step 2: I Can't Find 1/4" Elastic Material Anywhere!!!

This has become a major issue. But the solution is simpler than many would believe. Learn to think differently, sideways. Also, always pay attention; you never know when some common daily activity holds the key... Many of those who read this who work or have worked in an office environment are about to kick themselves. Ever notice the tras cans at your desk? And that trash bag never falls in? Ever See the cleaning crew change the bags? Those 12" rubber bands are almost a perfect fit the elastic. They are a bit thick, but usable. I did a remix of the original post on thingiverse to allow use of thicker rubber bands.

Step 3: The Pattern

I am including a pattern as a template to cut out the material. I am not a seamstress. I tried to remember from watching my mother sew, but that was probably five decades ago. So if you want to correct the pattern, feel free. And be aware that it is more a guideline than an exact design; actual outside dimensions would change base on material's thickness. If the jpg file is printed actual size, it should be correct - this can be verified by measuring the width of the inner square (135mm).

Step 4: Assembly

First, print the plastic parts. This can be done in petg or pla+/plapro (regular pla may not be flexible enough).

Print the pattern. I then cut the pattern out (outline only, obviously) from the page and pin it to the material.

Cut the outline from the material and remove pins and pattern.

Fold the material over crease line (I secure with a pin) on each side).

I prefer to pin the material temporarily around the frame, then sew it. This ensures a good fit.

Don't forget to remove the pins.

Step 5: Final Thoughts


If someone else wants to take up the mantle of trying to present this to health care workers, the best of luck to you.

To everyone - Stay safe and healthy, it's still flu season out there and less than half of Americans get their flu shots. Just sayin'...