I made this air filter for my shop this week based on a design by u/No_Distribution_7368 . I've been looking at different DIY air scrubbers for years, and their design was so smart I had to try it. The main advantages to this design are: a powerful motor which allows you to use three filter stages without sacrificing CFM low cost. The fan was $60 on amazon, and the ability to use a very coarse pre-filter means a much longer life for the finer filters. I used MERV 6, 11, and 14 simplicity. I built this over the course of two afternoons, using scrap plywood. The only thing I did differently was using a washable filter for the MERV 6, and adding a power switch with speed control on the outside of the box, which was much easier than the (very clever) solution they had for adjusting the speed of the fan. I'm not an engineer or an HVACiologist but i'm very happy with this thing! It seems to work much better than the JET style scrubbers I've used in the past.…