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Description
Designed to utilize available medical or non-medical filter material to make an easy to assembly and sanitize mask. The mask can be custom heat formed using hot water. Requires half-inch elastic for bands. I am currently use 3.25 inch square of filti filter material filti.com. I was using a combination of non-fiberglass MERV 12 AC furnace filter and non-fiberglass HEPA filter cut to 3.25" squares to make masks. This appeared to be the best materials I can source locally to make something with higher protection than a cloth mask. I decided to use both because the cost of the HEPA filter is high and in high demand. The MERV 12 material is used as a pre-filter for the HEPA filter hopefully increasing the effectiveness and life of the filter. Please note disassembling the filters could compromise the filter media and reduce filtration ability. The filti material can easily be cut with scissors or a paper cutter. Other published mask designs cut n95 surgical masks to make filters for multiple use. This design also accepts this method.
The design prints without supports and one mask can be printed in 2 hours. I used an infill setting of 15% and 2 walls thick. The filters are cut to a minimum size of 3 inches square. Two 18 inch lengths of 1/2" inch elastic are used for the straps. For the small size, a length of 30 cm of 1/2" wide x 1/4" thick PVA foam weatherstripping is glued on with E6000 adhesive. For the medium, a length of 33 cm of 1/2" wide x 1/4" thick PVA foam weatherstripping is glued on with E6000 adhesive. For the large a length of 38cm of 1/2" wide x 1/4" thick PVA foam weatherstripping is glued on with E6000 adhesive. Glue the foam on so it slightly sticks out past the edge of the mask. This prevents the plastic from pressing on the user's face. The straps are adjustable and can be installed by pulling the elastic through mounting points. There are currently 3 sizes. The medium fits most. The filter V2 file is compatible with all sizes of masks. The filter V1 fits only the medium and large size. To insert filter, hold filter material over filter holder and push in from the inside of the mask.
Paper describing the effectiveness of various grades of AC filter and HEPA filter