True, but the MacGyver looking thing in the middle (or side,whatever) of your living room doesn't sit right with everyone. People pay money for aesthetics and take the hit on efficiency.

I'm seeing some 3d printed projects popping up that look to be filling this gap though.

We've been doing the $9 Amazon Basics fan with a good filter since wildfire smoke started really getting bad in the bay area, quite a few years ago now. We had a couple of big, expensive filter tower things, and they helped, but just a couple of the boxfans with filters duct taped on quickly and consistently annihilated PM2.5 and PM10 in our apartments.

Most surprising thing: all but one of those original Amazon fans is still running. They've had years of run time, at quite a bit higher stress than normal.

Filtering out the fines and ultrafines – the stuff that HEPA filters capture – makes a biiiiiiig difference in air quality.

A smaller supplementary unit made out of PC fans and N95s can do that. A 120mm Noctua fan's flow and pressure fits well for about three 3M Aura masks in parallel.

It's unhinged how good the air quality is in a room with a device like this.

I agree on principle. There are iterations on this concept that are much quieter, are visually more palatable, and still have high airflow.

Example: https://www.cleanairkits.com/products/luggable-ultra-air-pur...

That rules! Looks like you can do it with like 3 filters so it's more triangle shaped which makes sense. That's so stupidly simple too. Also aesthetically pretty cool - would look great in a workshop where it's like function first/don't hide the mechanism. And I feel like there's gotta be clever ways to incorporate something as simple as "box fan but the box is made of air filter" into like a coffee table or stand or something else clever? Probably you'd want to hide the filters inside if they look grimy before you actually need to replace them so you don't feel obligated to waste money by replacing too soon but sounds like a fun time to figure out how to integrate that in a hidden way into whatever's your vibe without looking jank

What is the advantage of this over just sticking a merv13 in your HVAC and running the fan for 15minutes every hour? (assuming it's rated for merv13)

In my bachelor days I put an air filter behind a box fan; women have higher aesthetic standards. mirv 8 works fine for me and I can pick them up grocery shopping, but my primary contaminant is a sheprador.

I’m not dedicating 1600 cubic inches of my living space to an ugly homemade piece of furniture that I have to rebuild whenever I change a HEPA filter. I suspect I am not alone in this.

I was wondering when one of the low-end 20" box fan vendors would add a slot for a 20"x20" filter... and it turns out Lasko finally did, creating an "AirFlex 2-in-1" product that's often knocked for price/noise but resolves the homemade look, for those that care.

I never get this take. Yes, you'd make this in a pinch but that thing is hideous to have around the house.

It's like telling someone they bought a car and pointing out that golf dimples with increase your mileage. No reasonable adult would have that thing in the middle of their living room!

My brother in law did this. It is boxy and ugly, but damn does it work.

I would build one but I live in Argentina and I have no idea where to get any of the components.

Everyone wants the sound of a box fan and the looks of duct taped cardboard sitting in their living room...

You can take it with you when your wife kicks you out of the house for making something so stupidly ugly even if its functional.