Slim and Adaptive Face Mask With Replaceable Filters

Many tutorials show how to make 3d printed face masks but I have not found solutions that adapt well to the face. So I decided to do a mask with some 3d printed parts and materials findable with ease. I hope it can be helpful to someone in these times when the pandemic makes finding masks impossible for many.

Be aware! It is not intended as substitute of certified masks, it can help only when these latter are impossible to find: have a mask like this is better than nothing especially if used with high protection filters.

I designed the mask in order to has:

• Perfect adherence to the face due to the possibility of be adjustable
• Small footprint with shape similar to disposable ones
• Good air flowing with double filter and relatively large filtering area
• Replaceable filters with the possibility of using p2 or p3 filters to have high grade of protection.

To make the mask you need:

• 3d printer
• Heat sealing machine (if you don't have it you can do it yourself)
• TPU flexible filament
• PLA filament
• Plastic bag of Filament
• Double sided tape
• Adhesive foam tape (draft excluder tape)
• 8x countersunk screw diam. 2.9mm *6mm
• A little piece of metal sheet

Step 1: Download and Print the File

You need to print the upper and lower belt and the 8 rings with TPU flexible material. The other models must be printed in PLA.

Use the same orientation of the blue models in the pics to get a good result.

Step 2: Assemble the First Components

Use hot glue to connect TPU belt to PLA joint.

Cut a strip of 4x80mm of metal sheet and insert it on the upper belt like in the image.

Step 3: Make Plastic Shell

For the plastic shell you can use platic bag with good thickness. I found perfect for this purpose the bag of 3d filament spools. It can also be used for food as written on itself, not bad.

1. Stretch foil to flatten it, use an heat source to get better result.
2. Dowload the pdf which contain the shape to use
3. Do a first seam with heat sealer machine only on one edge. It will be useful to keep aligned the two foil while using the shape to draw the contours on plastic.
4. Make other two seams along the oblique lines of the trapezium.
5. Cut the remaining edge

Step 4: Make Holes for Filters

Use the printed part like in the image to draw the hole. Use a cutter or scissors to cut both layers of plastic.

Step 5: Connect Plastic Shell to Frame

1. Bend the upper belt, this wil help to avoid wrinkle
2. Place 12cm of double sided tape on the plastic shell along the longest side
3. Make a mark at the center of the lenght, this will help for alignment
4. Accurately stick the shell to the frame starting from the center like in the image
5. Add further pieces of tape to completely hold the upper part

Step 6: Prepare Filters

I used 3M 6925 filters (P2r) to make the filters. I paid 5 euros for each one. With a filter you can obtain two for the mask.

Use the holder to draw the shapes on filter and cut them.

Step 7: Install Filters and Holders

Mount the filter holders on the shell using the 8 screws following the scheme on CAD image.

Place the filters in the holders.

Use the 8 TPU rings to securely hold the filters.

Step 8: Make It More Airtight

Use a foam tape (draft excluder tape) to get more air tight and confortable wearing.

It is better to use neoprene or rubber tape for better cleanability.

Step 9: Add Elastics

Step 10: Install Exhalation Valve

I also designed an exhalation valve to have less air resistance when exhaling but I prefer to not install it on the mask. According to medical indications, exhalation valve facilitates the exit of your droplets outside the mask which potentially can infect other peoples.
Install it if you want to use the mask for other pulpose, such as anti dust mask. The mask, as designed, already has good air flowing without exhalation valve but it can be increased enlarging filters and holder.

You can download and print the models using the same orientation in the image. The disk must be printed in TPU material.