I recently stayed in an apartment that didnt have central air so I created a corsi-rosenthal box since the smoke from the Canadian wildfires were so bad.
After 30 days of continuous use, with very minimal periods of it being turned off, this is what the filters look like!
It's disgusting yet also so satisfying to see the filters get darker from debris, dust, and dirt.
Edit: typos
We did one with just one filter on the intake side. Kinda like this one better. But it takes up more room than mine. I'll have to do some experimenting.
Corsi-rosenthal box is stupid efficient.