99.5% filtration efficiency Mask
Nurse Tommye Austin shares instructions on making a mask with MERV 13+ HVAC filters. Interestingly, she also appears to use Halyard sterilization wrap for the non-filter material.
Link: News Article with Step-By-Step Instructions
CDC face mask guide
The CDC now recommends use of cloth face masks and provides a guide on how to make your own. Please note that these masks, like most cloth masks, have very poor filtration properties compared to N95 or surgical masks. This site recommends a filtration layer, which you can find in some of the other guides.
Standardized Synthesis of Face Masks PRoposal
Nirupa Gadi, et al., provides a proposal of standardized face masks during shortages. The proposal goes over various filter material and construction.
Link: Standardized Synthesis of Face Masks Proposal
Quantitative Respirator Mask Testing
Dr. Scott N. Schiffres quantitatively tests HVAC filters, baby wipes, paper towels and coffee filters. HVAC filters (Filtrete 1900) was most similar to N95 mask material, but would have to be layered to achieve higher filtration.
HK Consumer Council consumer mask
HK Consumer Council released instructions on DIY face mask using paper towels and tissue paper. The claim that "two kitchen paper towels as the outer layer achieved over 90% function of surgical mask in terms of filtration of 20-200nm aerosol."
Link: HK Consumer Council face mask
3d printed adapter for snorkel
3D Printed Mask Tutorial
Dr. Chris Wiles provides a tutorial into making a 3D printed mask with furnace filters. One of the best DIY masks out there at this time. STL files provided on thingiverse.
Dr. Brianna Slatnick shows you how to make a respirator using an anesthesia face mask and ventilator in-line filter.
No Sew Face Mask
Raphaela Laurean makes a face mask using furnace filters. She uses MERV 13 filters that are able to filter particles down to 0.3 µm.