Simple DIY air filter can be an effective way to filter out air pollutants

I made one of those using a single 20"x20" filter on the intake side of a cheap 20" fan like that to use in my home office over 5-6 years ago. I use blue masking tape painters use to attach it to the fan. That tape comes off very easy and the filter does capture a lot of dust and smoke resin.

I'm really not seeing much advantage for building a box that uses 4 of those filters though. I doubt that increases the amount of air filtered much at all. You could run it longer before needing to change the filters, but we're talking just a few minutes of time at best and probably closer to no time saved at all, or increase in efficiency.

Much better description here:

https://cleanaircrew.org/box-fan-filters/