Half mask

thingiverse

TL:DR; Size L fits most men, size S should fit most women and children above 14 (guessing). Parts of the valve start with V, parts of the filter assembly start with F, second letter if present is the type (see photo) of filter that part is for: F - round on, S - pear-shaped one. Printable with minimal supports. Valve membrane should be used as a template to cut out from proper membrane material like silicone of some stiff foil. Long version: Right before the quarantines started in Poland I noticed there were no half-masks available to buy any more so I decided to make some for the filters I had around. Designed the parts so that there are minimal amounts of support needed. Support is required on: -F sleeve -F locks -masks themselves everything else you should print without supports, laying on the flat sides. I printed with 0.5mm nozzle at 0.16 and 0.2 layer heights. 2 perimeter walls are sufficient with nozzle this wide as the parts are really stiff and none of the masks I've made has broken yet. One full mask takes about 24h of printing time spread across different lots of parts. I'm uploading the parts in OBJ format since most slicers can process it and it's easier to edit than stl. If you want to you probably can skip the F rim and F grille since those are there only to protect the filter for longer use but are not structurally required. --If you have a different filter!-- I made this design modular so that if I (or anyone else) find a different filter that's available it can be mostly reused. The only parts that you have to design yourself are the filter enclosure (F rim, F grille and F lock) and possibly change the F screw a little bit. After printing: Glue the F rim and F grille together. Glue the F Screw and F backplate and F lock (first check positioning!) together. If you want to have the filter enclosure to be adjustable (rotation) after assembly, put ~2mm of silicone on the F sleeve so that it fits tightly into the masks left hole then glue the F sleeve cap on. If you have a round filter it's probably not important and you can glue the sleeve right to the mask itself. Insert the valve mani part into the shield and glue the shield and the main piece to the mask once you position it right. After all that gluing you should have a mask that looks almost like on the photos. One last thing is adding some foam around the edge so that it doesn't hurt your face that much and fits better. I used waterpipe insulation cut in stripes then glued that to the edges but I think any closed-structure (as in 'not letting air through') sponge/foam should work. Add a clothes band (slots made for a 20mm wide band) with the band thingies to adjust the length, tiny screw to keep the backplate in, and you're done! Usage: I've made about 18 masks so far for family and friends and all but one fit their faces (my sister has a crooked nose) so these should fit, if not you can redesign them or heat them up a bit and bend them to fit. If you find that the valve is not closing when lightly breathing in (sitting or being otherwise calm) screw the cap a bit in, if you find it's hard to breathe out then screw it back out till you find a proper spot. Remember to not touch your face when putting it on (first put your chin in, then stretch the band onto your heard) and spray the outside of the mask with alcohol after coming back home. As for filters: It has been debunked that "filters don't work against COVID-19". Now, what filter grades to use? FFP3 filters as close to 100% filtration as you can get so if you can get it go for it. FFP2 is around 95% filtration iirc so not that bad either if you don't have FFP3. FFP1 is ~80% so still better than nothing. Stay safe guys and let me know in the comments if any instructions are not clear enough or something.