This is an air cleaner that I built. It was surprisingly easy to put together and everything can be found at a local home center for under $100. I used a attic fan that moves 1600 cfm and three 1" air filters which I change every few months. Instead of using an on/off switch I used a 60 minute timer so I can leave it running when I do to clean up the air. I added three filters to the intake side. I vacuum the outside one off three or four times before I pull it off and then move the other two back with a new one to be added on the inside. I have am averaging only 3 filters per year. I purchased the attic fan from Home Depot. It is a Broan 1600 CFM Power Gable Mount Attic Ventilator. The current price on it is $99.00 which is up from $78 Two years ago. The noise level was very low out of the box, but I added some rubber spacers between the fan and the box, and also between the ceiling and the top mounts of the box to reduce even further. It runs very quiet which is nice because I let it run whenever I am in the shop.