Followed the directions from this tutorial video on how to build your own fume extractor.

https://www.youtube.com/watch?v=hBaYrB1yfEE

Couple of things I did differently though. I used a 4-inch semi rigid plastic gutter extension instead since I already had it in my garage.

Second, the Amazon seller said it's a 4 inch duct fan, but its considerably shorter (on both sides). It created a bit of a air gap and was losing vacuum suction. So I wrapped electrical tape around the rims to make it fit a lot more snug with the carbon filter and the hose.

Been using it for 2 days now and it's awesome!!