We don't have a diy com, so I'm posting on main.

Air purifiers are stupidly expensive for no real reason. Also they are out of stock everywhere due to the wildfires. I know for a fact all they are is a pressure optimized fan with a thermal protection circuit, and a HEPA filter, both of which are very cheap. I wish go make a few myself due to the inflated cost, but I don't wanna burn my house down. Anyone have any recommendations on how to do a thermal protection circuit for such a thing? Probably gonna use a fan from a thrift store or something as the base for this.