In the wake of the COVID-19 Pandemic, vital medical supplies are more difficult to obtain for healthcare workers. Respirators, like the CDC recommended N95 [1], are in short supply. Therefore, many communities have enlisted the aid of seamstresses and other makers to supply hospitals with alternative masks. At this time it seems appropriate to recruit all available resources to meet these critical supply shortages. As such, many 3D printing hobbyists are developing printable respirators that use common materials for filtering. The OS (Open Source) Respirator is a unique prototype respirator, that utilizes swap-able filters, with a theoretically longer (or easier maintained) lifespan than cloth masks.

Disclaimer: Like cloth masks, the OS Respirator is not intended to replace the CDC recommended N95 respirators [1]; however, the OS Respirator is designed to provide protection that is sufficient in the absence of something similar to an N95.

The OS Respirator utilizes a modular filter design, which simply means it is compatible with any of the filtering materials listed below:

  • 100% Cotton T-shirt
  • Pillowcase
  • Linen
  • Silk
  • Tea Towel

Viruses like COVID-19 and Influenza are transmitted through the air in the form of very small droplets called aerosols [4]. The materials above have been proven to be at least 50% effective in filtering those virus sized aerosols [2]. However, other materials could feasibly be used through modification of the filter adapter.

Face mask
The seal of the face mask greatly impacts the efficacy of any respirator [3]. Users should make adjustments to get the best fit for their face. Heat gun, hair dryer, or adjusting the CAD model before printing are all effective ways to adjust the OS Respirator.

[1] Center for Devices and Radiological Health. (n.d.). N95 Respirators and Surgical Masks (Face Masks). Retrieved from

[2] Davies, A., Thompson, K.-A., Giri, K., Kafatos, G., Walker, J., & Bennett, A. (2013). Testing the Efficacy of Homemade Masks: Would They Protect in an Influenza Pandemic? Disaster Medicine and Public Health Preparedness, 7(4), 413–418. doi: 10.1017/dmp.2013.43

[3] Sande, M. V. D., Teunis, P., & Sabel, R. (2008). Professional and Home-Made Face Masks Reduce Exposure to Respiratory Infections among the General Population. PLoS ONE, 3(7). doi: 10.1371/journal.pone.0002618

[4] Tellier, R. (2006). Review of Aerosol Transmission of Influenza A Virus. Emerging Infectious Diseases, 12(11), 1657–1662. doi: 10.3201/eid1211.060426