To protect others from COVID-19.
The latest information indicates that asymptomatic transmission of COVID-19 is a massive and under-reported problem. Millions of people could be spreading the virus right now without even knowing it. 
Though not considered effective at preventing infection of the wearer, home-produced face masks can reduce the transmission of pathogens from infected people, including those without symptoms, by catching infectious aerial droplets before they contact other people and surfaces.
In order to slow the transmission of COVID-19 by carriers with and without symptoms, Americans should immediately begin wearing face masks in public at all times. Unfortunately the supply of face masks in the United States is severely limited, and available commercially-produced masks need to be prioritized for medical personnel.
If you have a sewing machine at home, here's how you can help! Download a .PDF pattern and sew your own “Victory Mask.” Once you’ve made one for yourself, make more. Give them to your family, friends, coworkers, and anyone else who wants to reduce the spread of COVID-19. They’re easy to make and machine washing kills the coronavirus.
Remember: a face mask is never a substitute for following the instructions of your local public officials and health experts. Wearing a face mask won't prevent you from getting sick. It's about protecting others.
How to make a face mask using the Turban Project pattern, courtesy Deaconess Health
Watch this video to make the ProperFit Clothing mask (pattern above).