I have family and friends in the healthcare, military, first responder, and law enforcement so I was particularly motivated and invested to design a reusable mask with a disposable DIY filter that can be made out of a wide variety of flat filtration media, depending on use and exposure risk. My initial concept was to use HEPA vacuum bags, but in my research and prototype testing they proved to have a large pressure drop across high efficiency (99.99%) filters that made it difficult to breathe through, though possible. a reduced efficiency (95%) would be suitable for normal use and easier, though only slightly restricted breathing.

My design relies on the proven and tested filtration testing of whatever filtration media is used in combination with proper fitment and print quality. To aid in fitment and sealing, I created 3 sizes to begin with 1.00 (Small), 1.05 (Medium) and 1.10 (Large) - models include the size between the left side tabs. There are two tabs on each side that feature an integrated loop-back design. All models and sizes are designed for additive manufacturing, specifically for FDM... without the need for support material!! (all angles are roughly 45 degrees or higher). The main section contains all rounded edges for comfort and smooth printing, and is intended to be printed from TPU or PCTPE (or similar semi-flexible filament) to aid fitment and sealing, though can be alternatively printed out of any rigid filament such as PLA or PETG. To aid sealing, I have designed an optional improved snug-fit face seal for each size, intended to be printed out of NinjaFlex or similar ultra-flexible filament. The screw-on end cap fits all sizes of masks and I recommend printing out of a rigid filament like PLA or PETG for tightly securing and sealing the filter element against the main piece, though TPU or PCTPE would probably work fine as well. The filter element should be a 3" diameter circle cut or punched out of any suitable filtering media, placed into the end cap and screwed tightly onto the main mask. The optional face seal can be glued on; I recommend silicone (or similar RTV adhesive/sealant) due to its chemical and heat resistance as well as its flexibility.

 

Key benefits:

Reusable mask design

multiple sizes

optional improved face seal

DIY disposable filters

Designed for manufacturability

 

I do not offer any guarantee and this is not intended to replace tested and approved masks for clinical or personal use. I do not have the capability of testing, though any tests, results, or approvals of my design (submitted for consideration in mask shortage situations) will be the responsibility of the entity that performs or publishes them.

 

I claim creative commons Attribution-NonCommercial-ShareAlike (CC BY-NC-SA) rights for this design. Constructive feedback and/or improvement recommendations are highly encouraged and welcome. If additional or alternative features or sizes are requested or recommended, I will consider designing and submitting revised or alternative models.