And here's a website with a pretty comprehensive how-to that addresses concerns/reservations, additional and/or adjacent questions, offers different build styles, etc etc. cleanaircrew.org/boxfanfilter...
THE Corsi/Rosenthal Box FAQ - Clean Air CrewAnswers to the most frequently asked questions regarding the DIY box fan air filter solution, also known as the Corsi-Rosenthal box.cleanaircrew.org