The buck (mold) we tried printing on several printers, at both a high and low resolution. Low resolution still works well, although the mask is a little less transparent. If you are planning to vacuum form many, PLA is not recommended for the buck or it will deform under the heat. If you must use PLA, print with many perimeters and higher infill.
The filter clips can be printed in any material. Note their orientation, the outer clip should be printed flat, while the inner clip should be printed on it's side.
Pictures included of assembly process. Once formed, use a razor to cut out the mask -- usually I will do a rough cut to separate most of the material, and then come back slower to trim the excess. Use the razor again to cut off the slits in the mouth piece.
We are experimenting with filter material, but in the development process we sacrificed and dissected one disposable mask, which can be cut into ~10 inserts for this mask.
Take two such inserts, cut to approx 1 square inch -- keeping in mind the filter material might be directional -- place the first into the mask from the inside, and hold in place with the "Inner Clip". Then from the outside, put the other filter piece into the "Outer Clip", and snap them together. Two pieces of filter should now be sandwiched around the slit openings.
The last step is to add the elastic. We are trying a variety of different elastic bands, including some 1.75mm tpu (pictured). These have not been added to the mold yet, and are just being drilled - above the cheek bone and at the jawline which seems to give the best suction.
If you have access to a vacuum forming machine, please get in touch with us, as we are looking for help validating the design and replicating elsewhere.