With how bad air quality has been this year, I grabbed myself a DIY AirGradient kit so I can monitor air quality in my living space. It was easy to assemble and only required a little bit of soldering knowledge. I'm definitely not proficient enough at soldering as many components ended up crooked on the board. Still works though lol.
In the picture it's running ESPHome with the configuration from ajfriesen on GitHub.
I unfortunately don't, but it was basically just soldering everything together on the PCB. AirGradient provides build instructions if you get a kit.