You can do the same with regular air filters for your HVAC. Buy 4 that are square, the size of the box fan. Put the 4 filters on end into a box. Put it on the f

You can do the same with regular air filters for your HVAC. Buy 4 that are square, the size of the box fan. Put the 4 filters on end into a box. Put it on the floor or cardboard bottom. Place the fan on top blowing into the box. Obviously, duct tape the filters where they meet to keep the box from collapsing. https://www.digitaltrends.com/home/how-to-make-a-box-fan-air-purifier https://www.digitaltrends.com/home/how-to-make-a-box-fan-air...