I built a "Laminar" Flow hood using a 120qt tub, a fan, a 6qt tub packed full of polyfil as a pre-filter, a purple allergen 3m filter (as a face to disrupt airflow, a trash bag, some gorilla tape, some tubing, hardware and silicone. Works awesome. I have 0% fail rate on cultures done in front of it. I have thoroughly tested it using the "incense and bottle test" and there are no eddies or vortices.
What kind of "filter" are you trying to set up? My flow hood 'scrubs' about a 2 cubic foot area (the size of my workspace.) For the money if you are trying to do your whole house you can "stack" filters (the purple 3m have anecdotal evidence of being very effective when triple stacked. Many people were using them during Covid. It "purified" the air without damaging the HVAC blower motor)