Credit to @macrosbudt, who created the original post and gave permission to repost. I’m trying to blaze this. If it doesn’t work, that means the moderators rejected it.
Another design is using 2 20x25x1 filters, taping them to the sides of the box fan and then to each other so they sort of make a triangle, then cutting cardboard to make a top and bottom to the triangle.
This was discovered as a more effective design during the 2020 US west coast fires.
[Images from the first post: Post and two comments at r/lifehacks; transcript follows.]
Posted by u/Cheff_excelence: If you want an air purifier but only have $39, slap a 20x20x1 (inches) filter on the back of a box fan. [Attached photo of the setup for a visual example.]
Reply by DanceUnderMoonlight: That’s exactly what these guys did in China. They even have data that proves its just as good or better than the expensive name brand air purifiers. https://smartairfilters.com/cn/en/
Reply to DanceUnderMoonlight by Kurtta: Also to add that the University of Michigan did a test on this showing how well it performs against a regular air purifier. “Build a do-it-yourself air purifier for about $25” https://www.youtube.com/watch?v=kH5APw_SLUU
[Second set of images: A box fan with two air filters attached in a “v” formation to the back of it, forming a triangle; cardboard has been taped over the opening between the filters and the fan at the top to block unfiltered air from being drawn through the fan. End ID.]
WisCon used Corsi-Rosenthal Cubes to excellent effect quite recently. Definitely worth looking in to.
