Zamboni_Driver

There are alternate builds cleanaircrew.org/box-fan-filters/.

In past years, I’ve built one with only one filter that the fan pulls through. You need to offset the filter from the face of the fan still by 8" or so with a cardboard spacer to help it be more efficient. It worked.

I’ve also built one with two filters in a triangle configuration, that one worked well too.

This is the first year that I’ve built one that is actually a cube with 4 filters. They all work, the 4 filter one works the best, but it also takes up the most space.