Flexible TPU Face Mask (for 70mm Cartridges Elements)

thingiverse

Reusable face mask using standard 70mm respirator cartridges. The design goal is to create a reusable mask that is both small and comfortable, utilizing readily available 70 mm replacement respirator cartridges. These cartridges meet the Australian P2 standard, ensuring they filter out at least 94% of airborne virus particles down to 0.3μm micron size. Several designs were printed in PLA but were found to be too uncomfortable against the face. Alternative solutions like flexible silicone rims or self-adhesive foam were considered, but I chose to print my design using TPU (flexible) filament instead. This required modifying my CR-10 to use a MicroSwiss drop-in direct drive extruder, which provided excellent results after initially struggling with pushing flexible filament into the Hotend. The 70mm cartridges fit snugly into the mask housing without additional sealing needed. I have shared a link to a YouTube video showcasing the mask and installing the cartridge: https://youtu.be/EXwc5MQnyUk Other concerns include: Is there CO2 buildup in the mask? Testing by wearing the mask for extended periods showed no noticeable effect, with research articles suggesting that FFRs do not impose any important physiological burden during use. However, elevated P(CO2) is a possibility, and this design could easily be modified to accommodate an exhalation valve if needed. How long do the cartridges last? These are designed for heavy industrial use, but for general public use, they should remain functional for months. The labeling on the cartridges states a life of 5 years. How comfortable is the mask to use? While no mask is truly comfortable, especially after initial wear, comfort largely depends on the type of TPU filament used. Softer filaments can be achieved with proper printer and extruder settings. Heated reshaping with a heat gun can also make adjustments for a better fit. For sensitive nose bridges, adding a thin pad to the internal nose bridge area can provide extra comfort. The small clips for straps are modified from DCREEL's "Small Strap Clip" at Thingiverse: https://www.thingiverse.com/thing:264160. The direct drive extruder used is from MicroSwiss: https://store.micro-swiss.com/products/micro-swiss-direct-drive-extruder, and the TPU filament is sourced from Bilby Australia: Flexible (rubber-like) Filament - 1.75mm - White - 200g Spool (Part Number Flex175WhiteSML).