3D Printed COVID-19 Mask With Gasket (NOW WITH 100% MORE FLANGE!!!)

Introduction: 3D Printed COVID-19 Mask With Gasket (NOW WITH 100% MORE FLANGE!!!)

This Instructable is a stop-gap measure. This is in no way a replacement for proper N95 or N99 masks used in a medical setting. This is a measure that is being taken by makers across the country, possibly the planet, in response to insufficient medical supplies to combat the COVID-19 virus.

I was asked by a local agency to provide backup/emergency masks due to their dwindling supplies. I am using the "Montana Mask" currently distributed by the Billings Clinic Foundation.

I applaud the foundation for their work, but they have not made available step-by-step instructions on how to make these masks and, possibly, more importantly, information on what they are using for gasket material. The gasket is key to creating an effective seal between the face and the hard plastic. Without a proper transition material between the face and mask, the mask is rendered less effective. This would expose the person wearing it to the virus.

The Instructable here covers the assembly of an adult large mask. I have not been assembling many medium-sized masks and only have anecdotal experience with them. I hope to create a sizing chart for these masks in the near future.


3D printer

Filament (I am using PLA)

Computer to operate printer or upload files to SD card

1/4" flat elastic fabric

Weatherseal (I am using MD Auto and Marine Rubber Weatherseal, product number 01025, SKU: 4337401025)

Rubber tool dip

Ruler or tape measure


Small paintbrush

Clamp devices (I am using hemostat and paperclips, you could get away with just paperclips if you don't have the hemostat)


Filter (I am using a MERV-14 rated air purifier filter material, use MERV-13 or higher rated material)

Step 1: Get Your Printer Going!

**Update** I am including an updated filter holder/frame with a flange!

Thanks to Makethemasks.com, they have helped make a sturdier flange than the brims I have been using.

***Further Update with New Files***

(White mask pictures) I have met with several served agencies and they wanted a more secure way of holding the filter. What I came up with was to add a flange and cross member to the mask itself. That way, when the filter is put in place, it is effectively held from the front and the back. The individual I met to do the fit test said that the flange on the front side of the mask will also help provide a better seal.

(Black mask picture) Since I already have a pile of maks printed, I decided to make a retrofit kit to print and glue to the masks as well as give out to the first responders who already have the mask. I found that a layer of super glue is sufficient for this. If you wanted to make sure it seals, add a layer of plastic dip around the outside of the retrofit plate.

Step 2: Finish Your Print

**Update** This step is no longer necessary if you get the new files located earlier on the Instructable. The flange eliminates the need to print and retain the brim and thus makes finishing much faster.

I added the brim for two reasons. First, it helps the print adhere better to my build plate. Secondly, the brim, on the outside of the filter holder, seems to do a little better job sealing around the filter, so I decided to leave it.

CAREFULLY cut the brim from the inner "windows" of the filter holder. I found that cutting diagonally into the corners and then pushing the trapezoid shapes inward helps them break off easily.

On the mask part, the brim around the filter holder needs to be removed in the same way that the brim was removed from inside the filter holder. The little brim on the outside edge can be peeled off easily or left, your choice.

Step 3: Prep Your Gasket

For the large mask, cut a 16" piece of the weatherseal. I have had approximately 3/4" of material left over to be trimmed at the end. You could get away with using 15.5" pieces and have less waste.

Find the middle of the piece of weatherseal by using the very precise method of "folding it in half." This will help us put the middle of the weatherseal at the bridge of the nosepiece and have the joining seam at the bottom of the mask (under the chin area).

Raise the plastic strip covering the adhesive by pinching the weatherseal. Lift it up slightly and cut with the scissors.

Step 4: Put on the Gasket

Peel off an inch of the adhesive cover and start at the top of the nosepiece. I clamped it down with hemostats to get a good seal.

Continue to peel the adhesive cover off of the weatherseal and firmly press the weatherseal along the inner edge of the mask with approximately 1/8" hanging outside the mask. Continue around the inner edge until you run out of weatherseal. Restart the process back at the nosepiece and work down the opposite side of the mask. When you reach the bottom, trim the excess weatherseal to fit, but leave a small overlap. This ensures that there is no gap in the gasket.

The gasket tends to peel where the cheekbones meet the mask. I added two large paperclips to hold the gasket in place as I finish the seal.

Step 5: Finish the Seal

The adhesive on the weatherseal will not stand up to repeated use. Add a coating of rubber tool dip to the outside of the mask where the weatherseal and PLA meet. This improves durability.

Pay special attention to where the two ends of the weatherseal meet at the bottom of the mask. Apply rubber along the entire area where the two ends meet.

Let dry for 30 minutes and then remove the hemostat and paperclips. Apply a second layer and let dry.

For quality control, shine a light along the inner edge of the gasket and look for any tiny gaps, especially along the seam where the two ends meet.

Alternatively, if this mask is for your personal use, you could put the mask on, hold your palm flat against the filter hole, and breathe in. Any sounds of air moving across the gasket will mean the seal has a problem.

Step 6: Add Your Elastic

Cut two 18" pieces of the flat elastic fabric. You may only need 16" but since I am distributing these, I wanted to give the receiving person the ability to trim the bands to fit them.

Thread the elastic through the holes in the side of the mask. Once they are sized to the wearer, tie the elastic in whatever manner you choose and trim the excess elastic.

Step 7: Install Your Filter

Note, I am using a coffee filter for the demonstration, as I am waiting for my filter material to arrive. A coffee filter might be fine if you are working with sawdust or some other large particles. If you are giving this mask to a first responder or medical professional, please DO NOT use t-shirt, bandana, coffee filters, or other unsuitable materials! Source out a filter that will provide an appropriate level of protection!

The Billings Clinic Foundation suggests that existing clinical masks can be used as a filter by cutting them into 2.5" squares. A person can get 6 filters from one mask, thus extending the current supply.

I will be using a MERV-14 rated air filter which is cut into 2.5" squares.


After delivering the first batch of masks, the method putting the filter in from the front worked 90% of the time. The gasket was so effective that when the user was breathing very heavily, the pressure displaced the filter.

If you add the filter from the back, still having the finished side pointing toward the user's mouth. This method will keep the filter in place even with heavy breathing.

Step 8: Wear It With Pride

To attain a proper seal, your face should be clean-shaven. I am not a first responder, so I am still a little partial to keeping my scruff around as long as I can. But if it comes down to staying healthy or keeping the facial hair, I will shave.

That being said, the gasket still provides a fairly good seal around my short facial hair. I would still recommend only using these in a serious fashion with a clean shave.

The Billings Clinic Foundation recommends to change the filter and wash the mask with soap and water between each use.


PLA mask may be slightly adjusted to improve fit and seal for each user! Using a hair dryer on a low-medium setting, you can gently heat the plastic and press lightly on the plastic to change its form. I have also seen that dipping in very hot water can get similar results.

Things to keep in mind:

1. Do not overheat the plastic

2. Do not apply heat directly to the gasket material

3. Take it slowly as not to damage the mask

4. Redo the Quality Control step by sealing the hole for the filter with mask on your face. Breathe in to see if the seal has improved

5. If you hear air leaking, run your fingers along the edge where your face meets the gasket, a change in sound may show you where a leak may be and further heating and pressing may be needed

6. Also perform an air leak check by running your fingers along the area you heated and formed. This will check to see if there is any delaminating between the layers of the plastic

Step 9: Future Considerations

If you are printing one for yourself, congrats, you are now covered.

If you are now turning your wife's craft room into a small cottage industry and making a dozen or two of these per day to distribute, you might want to look at sterilization.

I am distributing these to my served agencies with each mask inside a quart-sized baggie. I am putting each baggie under my 200 watt UV light for half an hour.

Is this method perfect? Probably not.

Will it kill all germs and bacteria? Probably.

Will it keep one person from sneezing and infecting a box of 30 masks in one go? Yes.

1 Person Made This Project!


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1 year ago

I can't be bothered to amke an Instructable for it and since you already provided the copy of the Montana Masks:

The print settings need to be 0.1mm or thinner for the layers.
In your pictures the rough surface from the thicker layers is evident.
Although bleech is suitable to clean these PLA masks in a rushed environment it is hard to ensure these gaps are properly cleaned.
Even the best sanitised looks unacceptable once too dirty to clean.
I have printed a few of these when they first appeared as downloads from the creators and can olny stress out the importance of thin layers.

Do not use any other material than PLA or PETG for these mask!
ABS and other exotic materials won't tolerated the required sanitation chemicals!
On top of that PLA only needs to be placed in hot water to make it playable enough to get it into a perfect fit for any face.

The seal around the mask is quite vital and although I have not published it yet I would like to share it here:
Using rubber like seals as used for home improvement works to some extend but these soft surfaces are noturiously difficult to clean once actually dirty.
On top of that, the glue used on these strips does not really sanitizers or just a lot of water contact for that matter.
This is my way of doing things and please everyone feel free to try and share it, just don't go ahead and post it as your brilliant idea please ;)
Use 120 or 180 grit sandpaper along the contact area of the mask.
It does have to look polished, you actually want to create a rougher surface here.
Get some silicone chaulk and some spare nozzles for the cartridges.
Use one nozzle to cut into shape for the contact area.
You want the area that touches the mask in the moving direction first to be a quite tight fit - a tiny bit of play though to make it around the corners properly.
On the other side the silicone shall have a slightly larger opening in the nozzle.
You want it a bit like an inverse V - a wide base on the mask and a thin top.
If you don't get a nice and smooth finnish at your first two or three masks you can use your finger and some soapy water to give it a smooth and clean finnish.
The silicone, once fully cured tolerates all cleaning chemicals out there, won't come off easy and is actually rather pleasant on the skin in terms of softness a getting a "grip" feeling on the skin.

In terms of proper filter materials:
N95 is the way to go.
I had several doctors who were more than happy to make good use of my donated mask after getting proper care and handling instructions.
Only clinic did a leakage and breathing test on a mask using the silicone seal and a filter insert with again a thin silicone layer to provide a seal - same on the surface of the mask with the filter material sealed between the two silicone layers.
Filter material was a cut section from a N95 rated mask (unsued of course).
Although not fully scientific and documented accordingly the clinic was more than happy with the results and stated their few official masks would not perform any better.
That is in terms of filtering quality and ease to breathe with the mask on for prolonged time.
I however need to stress out that despite using N95 or even higher rated filter material won't make this mask N95 rated!!
It might perform the same, give the same level protection BUT THIS CAN NOT BE GARANTEED, especially if you can't control the handling, sanitation or possible early material failures.
For personal use I found that these panty liners of the thin kind that our women use work quite well.
The gel inside absorbs moisture from the air we breathe out.
In return the filter quality improves as the moist surface traps things much better than a just dry surface.
Can't give you any rating though for these female hygine produtcs in terms of air filtering qualities to keep a virus out of your lungs.


Reply 1 year ago

Thank you for your input. I'm allergic to latex so using a rubber weatherseal around my face was a bit concerning. I like the idea of silicone much better.


Reply 1 year ago

I took the liberty of creating an optimised STL version of the original files from www.makethemasks.com.
Uploaded on Thingiverse and Sketchfab.
Reduced in file size, geometry and with the nagging overhangs on the mounts for the bands removed.
Feel free to use them.
In case this is not wanted please feel free to delete this comment or let me know and I delete it - just trying to help out everyone running the meters through the printer for a good cause.
Print time for just the mask in 0.1mm on my printeris about 5.5 hours.
just over 4 if I crank the speed to the max but I don't like risking it.


Reply 1 year ago

Thank you for sharing your info. I was wondering if you can make available for a larger mask with your updated design. My husband works at a hospital and he has a larger face, so the .stl file that I downloaded from your link is a bit too small. Can you be so kind as to upload a larger one, as the area around his cheeks and chin is too small and needs to have more room when speaking.
I am a Newbie and volunteering to help out to make these masks for him and his hospital. have no idea how to adjust the size to a larger one, any help would be sooo much appreciated.
I am so grateful for your support and your assistance and your replies.
God Bless. Lisa


Reply 1 year ago

Might be too obvious but have you tried to simply enlarge the print by 10 or 15% ?
You would have to enlarge the filter insert accordingly of course but it would be beneficial for the overall airflow.
And you can always heat the face part up with a hair dryer or by dipping it into hot water.
Once warm you can frm it, like pushing the sides outwards or inwrds for a better fit.


Reply 1 year ago

I have sent you a message. Please reply with your email address and I will send you the file directly!


Reply 1 year ago

Hi, Thank you, I just replied. Please check your inbox. Thanks !


Reply 1 year ago

I am no expert on latex allergies, but both parts of the gasket material are made from a synthetic latex material. Would that still affect someone with a latex allergy?


Reply 1 year ago

According to the American College of Allergy, Asthma & Immunology: "Natural rubber latex should not be confused with synthetic rubber made from chemicals. Synthetic rubber products, including “latex” house paints, are not made with natural latex and do not trigger allergic reactions in people who are allergic to products made with natural rubber latex."
So we're good.


Reply 1 year ago

Thank you for your quick reply. I was concerned about the idea of giving these to people who worked in hospitals where latex is not allowed.


1 year ago

What are your printer settings as far as wall count, wall width, and infill?


Reply 1 year ago

I am using Flashprint.

Here are all of my settings:
Layer height 0.12mm
First layer height 0.20 mm
Perimeter shells 3
Top solid layers 4
Bottom solid layers 4
15% infill
Hexagonal pattern
Combine infill every two layers
Print speed 50mm/s
Travel speed 70mm/s
Extruder temp 200 C
Platform temp 50 C

Hope that helps!


Question 1 year ago

Thank you for the awesome description, I wish someone can do a video on the proper profile settings for slicing on Ultimaker Cura for Eryone Thnker S 3D printer for both PLA and TPU especially for a Newbie like me ;-( Pls Verify if this is correct for printing with PLA 1.75mm. I have attached 8 screen shots of my Profile Slicing settings on my Ultimaker Cura 4.5 or the PLA Material for my Eryone Thinker S 3 D Printer.

These are the setting for PLA 1.75 mm I have inputted. I am following the order of the settings on Ultimaker Cura so I don't make any mistakes. - I just want to ensure I placed these in the correct place: changed the Layer Height to: 0.3 mm and Initial layer height to: 0.3mm and Line width to 0.4 mm and (Wall line width) to 0.8mm, outer wall line width to: 0.8mm and Inner Wall Line width to: 0.8mm and top/bottom line width to 0.4 mm . Then I adjusted the Shell Wall Line Count to 3 > Top layers: 3 and Bottom Layer: 3. I change the wall Line count to 3 for the shell and the Top and bottom layers to 3

As far as Printing on TPU, Pls help very what changes I would need to male on these PLA settings. I know the Infilled needs to 10-15% and I will also need to change the Print speed at 40 mm. Is there any other changes that needs to be made?

I was wondering if anyone can share their workable Ultimaker Cura 4.5 completed G file for e Evryone Thinker S printer for both TPU and PLA to make these masks. I would really appreciate it! i have been up all night trying to configure this and not sure if I have it configured correctly. I wan to make these Masks for my husbands' hospital as they are running low on PPE. Thank you soo very much!

Screenshot 2020-04-11 15.10.54.pngScreenshot 2020-04-11 15.12.54.pngScreenshot 2020-04-11 15.12.43.pngScreenshot 2020-04-11 15.12.17.pngScreenshot 2020-04-11 15.11.38.pngScreenshot 2020-04-11 15.11.17.pngScreenshot 2020-04-11 15.11.07.pngQuality-Screenshot 2020-04-11 15.56.01.png

Answer 1 year ago

I wish I had an answer for you.

I do not have any experience with TPU either. I think it would awesome to print in TPU because that would mean I would not need to make the gasket (the most time intensive portion of the process).

I think if you could use a dual extruder machine and do the front part in PLA and the back half in TPU, that would be a great thing!

Good luck!


1 year ago

Can you post a link to what you bought for a filter? I can’t find anything..


Reply 1 year ago

The filters are from a company called High Tech FlowMark out of Billings. The problem is that if you are not working directly with a hospital, they will not send them to you. Too many people have ordered them and resold them for much higher costs. So they are working on making the product available for people on the front lines.


1 year ago

Get your mask to the dry cleaner !!! ;)
I had a request from a small clinic about options of unattended sanitation of the masks.
Preferably dry...
A suitably sized box with enough germicidal UV lamps, as used quite often for fish tanks, does the trick here.
A thin metal grill to place the mask(s) in a single layer.
A lightproof box around it and on the inside wall enough lamps to provide a full coverage of low wavelength UV light to all surface areas of the mask.
You can also use suitable reflectors (like copper foil) for the UV and use less lmaps.
However, I used used 2 20W lamps on ceiling and fllor plus one 20W lamp on the the left and right side wall.
This was for a simgle mask test.
The usual tests in petri dishes as done by some doctor in the clinic revealed that an exposure time of 20 minutes produced a mask with no detectable bacteria or viral traces left.
Be aware though that results will differ depending on your light source, setup and proper placement.
It is highly advisable to perform some standard tests with the mask to establish a proper exposure time and to ensure ALL surface areas are free of hramfull stuff.
Once a consistent time for the exposure is found this time should get a 20% safety margin added!
Always prefer alonger exposure time over rushing it and if in doubt and in a hurry use standard bleech solution and the traditional wet clean of the mask.


Reply 1 year ago

Thank you for your comments.


Question 1 year ago on Introduction

I was wondering what the plasti dip is used and how. I think it is used to make it so you dont have to sand them and smooth them out. Please include this.


Answer 1 year ago

The plastidip is used to esure a seal around the gasket. There is a slight gap between the two ends of the weatherseal. The weatherseal's adhesive also comes off, so the weatherseal also adds another layer of adhesion. Check step five and let me know if that makes sense for you.