After reviewing the billings mask I created modifications with the intent of forming a tighter/more comfortable seal to the face, better securing the filter in place, and allowing for more airflow. Due to limitations I find in FDM printer filaments my aim with this design was to provide a print that could be molded in silicone, and cast in a polyurethane resin that would make for a better material to sterilize and protect the wearer. To better secure the filter in place I created a locking bar that would be placed inside the mask preventing the filter piece from falling out, which is locked in by two clips on the inside of the mask. The goal of all of this was to create an easily producable mask that could be supplied by materials found at an individual's local grocery store but still provide better protection against the spread of disease over a cloth surgical mask or bandana.

After printing, sanding, and post processing to improve surface finish, I created a silicone mold of this model using TAP Plastic's Silicone RTV System which cured for 24 hours. Afterwards I made a resin cast using the TAP Plastic Quik Cast Polyurethane resin. This resin has a 30 minute cure time which allows more masks to be created in the same time  compared to the 4-5 hour print time on my traditional FDM printer.

 

For air filters I used a Honeywell Allergen Remover Replacement HEPA filter, with emphasis placed on a filter that captures up to 0.3micron particles. I dismantled the frame of this filter to allow me to cut 3 inch sections to be used with the mask.

To provide a better seal I used Frost King EPDM D-Profile Self-Stick Weatherseal, and designed a gap running along the rim of the mask intended to grip the weatherseal. Due to the weakness of the self-stick adhesive I'd recommend using a superglue to coat the rim prior to applying. Once again, this may not be the best material for medical devices but I wanted something that was easily accessible to the general public during the lockdown.

The mask uses antibacterial non-latex rubber bands or elastic to secure it to the wearer's face, tied around the mounting holes on the sides.