A YouTuber, Joel Creates, recently developed a filter that can be assembled from furnace filters, 3D printed parts, O-rings and PC fans: https://youtu.be/GpA7-EJpKWU

Files can be purchased by backing the Kickstarter but they won't be sent until November: https://www.kickstarter.com/projects/joelcreates/oddcube-air...

I think this could be substantially cheaper than a build based on a PC case.

> The total cost of these filter boxes are somewhere around the $300-$350 CAD range

About the same as a Coway

If you want to DIY these there's a FOSS (GPLv3) parametric builder web app that will output files for 3D printing, lasercutting, or handcut foamcore and calculate the performance of different configurations for you:

https://www.filterboxbuilder.com

There's no real performance difference between DIY and metal PC fan filter boxes, just durability.

I built something similar to the boxfan and 4 air filters when I'm doing woodworking, especially sanding. They work pretty well for that if you are on a budget.

This would be a neat thing for case makers like coolermaster or corsair to do a one-off of while the self build market is slumped.