just an update on this filter- i remoned the filter material that i rolled up and stuck inside the plastic cage. it seemed to constrict airflow. it seems to be more efficient if the air can breath out evenly through the whole filter. I also addded a second layer of carbon filter, it didnt start to stick, just an extra layer of precaution. Its still working like a champ. but my cost is plus $10

this can be scaled up or scaled down depending on the size of your room.