Open Source Parametric DIY Air Purifier Builder (filterboxbuilder.com)

Supports 3D printed, laser cut, and hand cut designs.

Shows CADR, total dBA, cost to operate.

Supports MERV13 HVAC filters and Ikea STARKVIND for places those are hard to obtain.

Includes fan P-Q curve, CADR, and ACH measuring tools.

Handy in wildfire season.