I have one made by a friend. He had one on each end and there was no dust. I use just one and it works pretty well. there is a big fan like on a furnace, but not as big, in a box made from plywood. there is a filter on both sides of it. The fan exits the top of the box. The motor has multiple speeds. If I am sanding a lot, I turn it on high. It sucks all the dust to the filter and none blows out the top. I have no windows in my shop and this works very well. Also stops the problem of eating dust when you are sanding. It works very well. If you are interested in making one, let me know and I will take pictures of it. Wouldn't cost a ton to build. Sure is nice though. I may build a couple for the room I am building the Long EZ full scale in. Boy can that fiberglass dust travel.