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English text:

Update 09/04/20: 

I made some improvements in the Cover_Filter_Box

Update 03/04/20:

Some people were unable to make the membranes because they were too thin. I changed the thickness of the membranes and the Cap_Valve. If you have problems with membranes, print the new membranes and the new Cap_Valve. I made some improvements in the mask.

English text: Update 02/04/20:

Some people have reported to me that they have difficulty mounting the filter on the mask. I made a new filter holder, with a thickness greater than + 0.2mm where the gasket rests. Some people do not find the seals for the filter. I made the seals that can be printed in TPU or TPE "better the TPE". Some people can't find 3M filters. I made an adapter to mount a 3M 2138 P3 R or 3M 2135 P3 R filter. Some people asked me to use a hygrobac filter instead of the 3M filter.

I made an adapter and a gasket to be able to mount the hygrobac filter.

Hello everyone, in this terrible moment in history, COVID-19 has combined the ideas of many makers to help the whole world overcome this moment of crisis and limit the death of people as much as possible. I made a prototype of reusable mask with interchangeable filter. The mask can be washed in water and 5% bleach. The filter used is a 3M 5935 P3 or 3M 5N1, certified with the filtering percentage equal to 95% FFP3, the highest possible. The mask is made up of 3 parts and is simple to make with FDM, SLS printers etc... The mask is composed of: Filter, Mask with valves, Soft part. The mask must be printed in PLA or PCL with supports on the part where the filter is to be installed. “see pictures”. The soft part must be printed in TPU or TPE "better the TPE", to make it adhere better to the face. The filter must be printed in PLA or PCL with supports on the part where the filter is to be inserted and on the part of the fixing. “see pictures” The valves work with two silicone discs with a thickness of 0.20mm and a size as in the photo. As an alternative to silicone it is possible to print TPU or TPE discs "better the TPE", it is necessary to use a PEI or GLASS "smooth surface" printing surface. The smooth part is the part to be placed on the mask, the part that closes the valve. The valve must be printed as shown on the photo on a PEI or GLASS "smooth surface" surface. DO NOT print these parts on a rough surface, the valve will not work! The exhaust valve must be inserted in the mask, use glue to guarantee the seal. In the part of the PLA mask where the TPU or TPE part is to be connected, it is recommended to apply some glue. This will ensure the two sides to be airtight. If the TPU or TPE part does not adhere well to your face, apply some Neoprene Stripping with adhesive, 15 or 20mm wide and 3mm thick. I made three sizes: small, medium, large. Only the soft part changes according to the size that best suits the face. To keep the mask on your face, use elastic bands 4 or 5mm wide. Excellent elastic tailoring, made of cotton. At the base of the filter holder, a rubber washer "one for plumbing, for taps" must be applied. Dimensions, internal 35mm external 45mm thickness 2mm. The supports must be added manually in the slicer, I used Simplyfy 3D, which allows the manual insertion of the supports. I am working on additional filter holders to be able to use other types of filters, such as the 3M 2138/2135 always P3. The use of non-certified filters is not recommended, the exclusive use of commercially available certified filters is recommended. Attached you will find the images relating to the mask and the print positioning.


1: First install the valve, take the Cap_Valve and insert the small membrane with the smooth part facing outwards into the seat.

2: Take the Base_Valve and insert it into the Cap_Valve, pay attention to the insertion, press on the center and insert it straight up to the bottom. Be careful not to break the central pin.

3: Test the valve with your mouth to verify proper operation.

4: We take the mask and insert the large membrane into the central pin, with the smooth part facing the cross. We bring the membrane to the bottom of the pin, pressing lightly on the central edge.

5: We take a nail with a large head, heat the nail head slightly and place the hot nail over the central pin, so as to slightly dissolve the plastic. In this way the membrane can no longer come out. Be careful not to dissolve too much plastic or the membrane will no longer work. Check that the membrane turns freely around the pin.

6: Take the valve, insert it in the mask, pay attention to the direction. If you are not sure that the valve is well attached to the mask, you can put some glue on the edge of the valve inside the mask. "I have not used glue".

7: Take the soft part and insert it carefully into the mask. If the soft part fits easily into the mask, apply some glue to the mask before inserting the soft part.

8: We conclude the assembly by applying elascites on the appropriate supports.

Your mask is ready, let's proceed with the testing.

Put on the mask and make sure that the soft part adheres well to your face, otherwise, change the size of the soft part or apply some Neoprene Stripping with adhesive, 15 or 20mm wide and 3mm thick. With the mask on, cover the front of the mask with the palm of your hand, where the filter is to be installed. Try to breathe, if the mask adheres well to the face, you will find it hard to breathe and you will feel the air entering your face. Now let's try to exhale, you will feel the air coming out from the exhaust valve side.

If the mask works we move on to installing the filter, if not, check the previous steps again.

We take the filter holder and apply a rubber gasket with a diameter of 35mm inside and 45mm outside 2mm thickness "look the photos". We turn the filter holder and insert a 3M 5935 P3 filter, close the filter holder with the lid, pressing firmly all the way.

We install the filter on the mask. Try the mask again by placing your palm on the filter and trying to breathe.

The project is given free, the sale for profit is not allowed, it is not allowed to make changes to the project or drawing. The mask is NOT CERTIFIED and is not a MEDICAL device. Perfect functioning is NOT guaranteed.

If you liked my work and it was useful for you, you can contribute by leaving a tip, thank you.

Print Settings






20 / 30 %




English: The membranes and the complete exhaust valve must be printed with a resolution of 0.1..! Don't change the print resolution or they won't work! Use a 0.25 or 0.4 nozzle. Do not use larger nozzles. The 0.25 nozzle is the best. Create supports as in the photos. 

Design Files

File Size

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