Gordo Tek on youtube has a nice build for a very affordable Flow hood that was under $100 at the time;
The purpose of a flow hood is to create an environment of net positive air pressure with clean air, the HEPA filters filter out most particulates and spores that are naturally found in the air, this helps to maintain cleanliness in a nice little bubble infront of your flow hood allowing for more relaxed contamination control procedures.
There can be anywhere from 1,000 to 10,000 or so spores in the air from dormant fungi, pollen, and even bacteria that gets everywhere and makes up a good portion of our ‘dust’ that we clean. So it’s important to maintain proper cleanliness, and one relatively easy way to do that is through a flow hood. The other option is sterilizing and ensuring that the air quality is highly clean.
Either way, it does help to have clean air.
And this is a nice tek for a cheap Flow hood that’s also pretty robust as well.
Theoretically, you could just use a hepa filter and a box fan if you want. Results may vary dependent on many factors like airflow itself.
There’s great content out there on the internet providing an affordable DIY flow hood for people who want relaxed controls on a budget.