Prices for AQI meters have skyrocketed. I bought one from Walmat 2 years ago for US$30 and the same one is currently US$110.
I haven't added a TVOC sensor yet (it's in the mail), but the dust sensor is in.
Runs on an ESP32 and programmed with Arduino (code attached).
Designed to be printed at .2mm layer height and .4mm width - i.e. walls are 1.2mm thick. Also note that support is not needed.
I connected 2 resistors from VBAT+ to an analog-in to take voltage measurements to provide a batter meter on the display.

Parts

• ESP32 TTGO T-Display LCD
• PMS5003 Dust Meter
• 3.7-5v step up converter for PMS5003
• 3.7v LiPo battery
• M2.5 screws or whatever you have handy
• 2 x 1K+ resisters, as long as they match (optional - for battery meter)

Future

• Bigger battery - the current one is 500mA and only lasts a few hours
• better lid to hide the screw holes - I'm still learning how to do this better

Feel free to customize on tinkercad:
https://www.tinkercad.com/things/06m8mnwu8Eo

Creality

Ender 3

No

No

0.2

10%