3D printed FFP-Mask

starting print, with big rim to make sure no warping occurs, 65% infill material:ABS
finished print part1 ...the face piece
finished print part 2 ...the filter frame
the printtime is fairly short with a layer height of 0.3mm (filter piece)
1*) here the first fit with a cut latex rubber glove as "airtunnel"
2*) the latex rubber glove acts as airtight seal between face and filter and clamps the filter to the filter frame
3*) scrunchies to fast mount the filter without tools
finished mask with 2 HEPA filters
4*) nylon strap that holds the mask in place (rendered)

The Inspiration

was the demand for a FFP-Mask for self protection so i do not need to rely on masks on the market and the idea that if the mask is working as intended, an alternative for local healthcare personal in case the supply of certified FFP3 Masks runs out.

What it does

It is a 3D-printed, reusable FFP-Mask with a changeable filter that should in theory be equivalent to a FFP3 mask (depending on the filter material).

How I built it

The design is done in Blender, an addon called FaceBuilder from KeenTools, a 3D printer and some household materials. It is a custom tailored product using photogrammetry with a photo series of the individuals head from different perspectives. The addon helps to easily[^1] recreate a 3D head model as reference for the mask. The most important area is the surface where the mask comes in contact with the skin to achieve a perfect fit (nose, cheekbone, cheeks, chin).

The mask consists of two parts, the face piece and the filter frame.The face piece is sealed with a latex[^2] rubber glove from top to bottom. This "rubbertunnel" guarantees an airtight seal from the filter to the skin (seen in pics 1* and 2*) and eliminates the possibility to leak air or particles through the 3D printed parts(these act only as skeleton). The filter itself is sandwiched between the face piece and the filter frame, thus having a perfect seal from filter to face. The filter material is a HEPA filter cut from a vacuum cleaner bag. The effective filter area on this model is 76x76mm (where air can pass through unhindered) and is easy to breathe through even with 2 filter layers. The filter itself is 98x98mm; the clamped 11mm on each side of the filter make sure it does not slip out even when breathing heavily or coughing. The filter frame is mounted with 9 scrunchies(rubberbands) 3*) to have enough force to push the filter against the face piece. No tools are required to change the filter.

The mask is held in place with a single "V" shaped 2cm wide nylon strap 4*) attached to a buckle.

Challenges I ran into

photogrammetry or measuring the face proportions, the process to get a perfect fit. I was not happy with point cloud generated meshes. They need a fair amount of pictures, then there is the problem with lighting, unless you are in studio conditions to get acceptable results; i only used the 8MP front camera of my phone to make the photos.

What I learned

[^1]: The FaceBuilder addon is much easier than most methods to accurately measure the face proportions, since everyone has a phone nowadays, so no fancy equipment is required... with a good camera, the knowledge of the sensor size and focal length im sure you can accomplish the reconstruction with less than 10 photos.. no need for cameras with depth sensors only a handfull of phones have... I now know what a scrunchy is ^^

What's next for the 3D printed FFP-Mask

Provide masks to local hospitals and doctors in my area if the supply of certified masks runs out. Im including a step by step tutorial on how to make this Mask for yourself and your area. This production is only scalable to a certain extent, but possible with the help from a strong 3D-printing Community. The free license for FaceBuilder is limited to 30 days, so the idea is to contact KeenTools for a cooperation to promote their Addon and find a solution for a license model for people using it to fight covid19.