I created a facemask that gets air from an air purifier. The Air Purifier used a MedifyAir MA-10.
The air purifier is rubber banded and taped using special sized bands to a section of a plastic bag.
The plastic bag is rubber banded and taped to a 3d printed hose adapter
The reason that I use a plastic bag was to allow for rapid breathing beyond the rate that the purifier could provide. The bag could provide a reserve that would be drawn down when I breathed quickly during times of exertion and would be refilled between breaths. I built this setup after I realized that riding my bicycle during bad-air days with high AQI values would cause me to go into AFib. When I starting using this mask connected to an air purifier, I could sustain riding my bicycle in less clean air for longer periods of time without going into AFib. The hose I purchased was a replacement hose on Amazon for the Broad AirPro Mask hose link
The mask is a 3M mask with a vent for exhaling here. I punched a 14mm hole in it. I purchase hose adapters from here that I glued to one-way valves here. With two one-way values, all inhaled air would come from the air purifier (or the N95 mask) and all exhaled air would go through the exhaust one-way value (or the mask).
I also attached a lanyard to this with some nylon string woven through some holes in the air purifier. The reason I did all this is here.