This is a video of Youtuber DesignMaker designing and building a motion-activated face mask that closes its mouth vent when people are detected nearby, or you aren't standing perfectly still. That sounds practical. Plus it makes you look like the lovechild of a wild threesome between Darth Vader, General Grievous, Bane, and that guy from Mad Max: Fury Road, so-- "That's a foursome." That goes to show just how wild a threesome it was.
Keep going for the video.
Thanks to Christopher C, who agrees sometimes you just need to really overcomplicate things.