Home › Blog › Making Our 3D Printed N-99 Mask

Much to our surprise (and that of our local 3D printing company), we got an immense amount of interest from patients and medical providers about our 3D printed N-99 mask. So much so, that I needed to put together a video about how to assemble it once it arrives. Hence, the video below and this DIY blog post!

The N-99 Mask

As I have written before, our N-99 mask started as a way for us to protect patients and our providers who must be in close contact with patients. The problem was that while we could source ridiculously expensive N-95 masks, every mask we bought would take a mask from a front line healthcare worker or first responder working with sick COVID-19 patients. Hence, we needed a way to build our own masks that didn’t take from that supply chain. In addition, the waste inherent in disposable masks is appalling, so an environmentally friendly mask was also needed, meaning it should be reusable.

I originally found a 3-D printed design online, but when we had a local 3D printing outfit fabricate it, it really didn’t work. For example, it was supposed to use a Roomba vacuum HEPA cartridge and this didn’t fit well; so the design was more concept than reality. However, we worked with the 3D printer to edit it to make it work, and our mask was born.

Surprising Interest

I made the quick video above and then I began to get deluged with medical providers and patients who wanted one. While I referred patients to the 3D printing company we used, most didn’t realize that the mask requires some assembly. Hence, I made the video below to show how it all works.

The DIY Video

Above is my 10-minute DIY video. First, you need to order the 3D printed parts of the mask from:

Nick Yosha | VP of Sales and Marketing
3D Printing Colorado | www.3dprintingcolorado.com
6901 West 117th Avenue, Unit 4 | Broomfield, Colorado 80020
303-466-0900 | [email protected]]

We make nothing off these masks. Instead, the 3D printing company gets all of the proceeds, which makes sense since they were kind enough to give our healthcare project priority and attention. In addition, I have been approached by people trying to make money off of this mask, which I’m not interested in at all. These masks and the STL file we created with 3D Printing of Colorado are for healthcare providers and patients, not COVID entrepreneurs.

The Disclaimer

I am not an N-95 or N-99 respirator expert. Hence, neither Regenexx, the Centeno-Schultz Clinic, nor Drs. Centeno or Schultz make any warranties that this mask will prevent COVID-19, nor that you will be able to make a mask that protects you from the disease. In addition, once your mask is complete, you will need to perform an OSHA respirator test to make sure that it is properly fit and that it works to meet federal specs.

What You’ll Need

1. The mask 3D printed in TPU material (the soft flexible material we used)
2. Roomba 700 series HEPA filter cartridges
3. Headwraps or another elastic strap (we used Modesso Thin Glitter Headwraps)
4. Superglue and rubber material-you may or may not need the rubber depending on how you want to build your mask and which version you get
5. 3/4 inch weather stripping (optional as well)

Step 1-Flapper Valve or Not?

We initially built our masks with flapper valves. This is a common feature of respirators as if you exert yourself, then you need to be able to exhale forcefully and this valve allows excess air to escape without having to pass through the HEPA filter. Given that these masks were not designed with the idea in mind that the person wearing them might need to protect others from his or her own water droplets, this made sense. However, there is now a national controversy now over flapper valves as they could allow a person with COVID-19 to infect others (this is theoretical, as frankly, the valve only comes into play when the person wearing the mask is working hard, otherwise pretty much everything goes through the HEPA filter). Hence, we decided that for clinical use, we should close our valves. We have also asked the 3D printer to not print the vent that forms the valve since the mask works fine for daily use without the valve.

However, if you have a mask print that has an air vent, then you can decide what you want to do. The video above will walk you through either sealing the vent and having no valve or creating a valve.

Step 2: Weather Stripping

Professional respirators tend to use rubber or similar to seal the mask to the face. Because we used TPU which is a soft urethane to print the mask, this is optional. For example, my mask works just as well without the weatherstrip rubber seal so I have eliminated it and filed the mask edges down to make it more comfortable. For others, you may need it to get a tight fit. See the video above.

Step 3-Add the Straps

Since, the elastic material for straps is hard to find right now given the fact that many people are sewing together their own cloth masks, we had to improvise here. Hence, we used Headwraps from the dollar store and cut them. Once you have an elastic strap, it just feeds through the side slots as shown in the video above.

Step 4: Add the HEPA Filter

The key part of the whole mask that makes it N-99 (able to filter 99% of particles) is the HEPA filter. These are the Roomba series 700 HEPA filters (part #4503461). Here are some options for purchasing:

• Walmart
• Amazon
• EZvacuum

This fits into the slots as shown and then clicks in on the other side.

Step 5-Test Your Mask

We did the OSHA Stannic Chloride test and used this product made by Allegro. There is a whole video on how that should be done:

This chemical smoke is very nasty, so be careful. The good news is that if the mask is working properly, you shouldn’t be able to smell the smoke and you shouldn’t cough (while everyone not wearing a mask will be coughing).

Who Should Use this Mask?

My target is patients and healthcare providers. On the patient side, we’ve had much interest from patients who are traveling on planes and in airports. This makes sense, as everyone is nervous right now.

The upshot? That’s it! This mask can be easily assembled after a few online orders or a visit to the hardware store. It takes 20-30 minutes at the most, so I hope this helps you realize your N-99 mask aspirations!

Chris Centeno, MD is a specialist in regenerative medicine and the new field of Interventional Orthopedics. Centeno pioneered orthopedic stem cell procedures in 2005 and is responsible for a large amount of the published research on stem cell use for orthopedic applications. View Profile