Fresh Air Filter

__Introduction__
After moving to LA, I am facing a difficult choice: death by lack of oxygen or death by illness-causing by ultrafine particles in the air. Neither of them sounds good to me. Why?
1. If we keep the window open, it is quite meaningless to keep the air filter running (As well as the AC, heater, etc...).
2. If we keep the window closed, toxic gas such as CO2, TVOC will accumulate and lead to undesired effects.

That is why designed this air filter. It takes air from outside the window, filters it with a HEPA grade filter, and forces the air into the room.

__Parts purchase__
Besides the parts you can print, you need to purchase the following items.
- HEPA filter: https://www.amazon.com/dp/B07DVTR1H7 (~$25)
- AC-DC adapter: https://www.amazon.com/dp/B01N51LI9I (~$12)
- PWM controller: https://www.amazon.com/dp/B072M2HKSN (~$20)
- Blower fan: https://www.amazon.com/dp/B07NRN46V4 (~$15)

__Install__
To be updated. Thingiverse lost my original writing when I fi