I have been wanting to make an air filter for a while. I couldn’t find a design that I liked until recently. The ones with multiple 1” filters and all the frames to hold said filters in place was more work than I wanted to put into this project. I finally found this one and knew that I had a design that made sense for me. So here it is. I originally wanted to hang it from the ceiling but this presented some major challenges. First I would have had to go up in the attic and sister some 2by lumber to my 1by rafters to have a strong enough place to anchor some eye screws. The second problem that I saw was that with the filter pointing downwards, some dust might fall out after turning the blower off that would pile up and then have to be cleaned up. So at the last second, I found some small casters in the drawer and put them on. Everything else is pretty basic just a 5/8” plywood box, biscuited together. The frame is made of window casing that is also biscuited and held on by a piano hinge and two draw catches. The filter is 20” x 25” x 4”. A 1 hour mechanical timer controls the motor.