**Disclaimer: Personal protective equipment (PPE) for use in the medical field is extensively tested and FDA approved; any non-FDA approved PPE should be used only in emergency situations when no FDA approved device is available. The information provided here should be considered educational in nature and not medical advice.

The spread of COVID-19 in the US has revealed a severely inadequate supply of personal protective equipment, especially N95 masks. The dwindling supply has lead some healthcare providers to search for creative solutions for respiratory protection. One emerging method is to purchase a reusable 3M 6000 series respirator for use in the hospital environment, however, the cost of replacement filters is high and availability of all N95 filter types is low. With the CDC currently recommending that masks be disposed of after every COVID patient interaction, the cost and availability of replacement filters makes use of these masks impractical.

Small HEPA filters are inexpensive, in high availability, and filter 0.3 micron particles with greater efficiency (> 99.9 %) than N95 masks (95%), making them at least as safe as CDC recommended masks. To utilize these filters I designed and 3D printed an adapter cassette to use inexpensive Roomba vacuum HEPA filters with a 3M 6000 series respirator. With the filter, PLA Filament, and silicone sealant, the final product comes to a total of about $3 each. I also propose that one mask port be capped with a 3D printed cover so only one filter needs to be used with each patient interaction.

In this video I discuss the design, assembly, and testing of a 3D printed cassette to adapt inexpensive HEPA filters to a reusable respirator:

If you would like to replicate this project here are the items that you will need:
1. Filter Cassette 3D Models
2. 3M 6000 Series Respirator
2. HEPA Filters
3. Silicone Sealant
4. Quick drying adhesive

List of tools that you will need:
1. 3D Printer
2. Clamp