I used a cardboard box with an air baffle system. I got the idea from searching on this site. I cut a large hole on each end of the box. The divide the inside of the box so air can pass through but not light.I need a passive intake Ventilation system for my grow room of 4' x 3'
Going to have 1000 Watt HID Light on 6 Plants of a Bubbleponic System
Carbon Air Filtering and Dehumidifier