I made this model and assembled everything in about 30 minutes. I decided to use a 5V USB fan that I had left over from another project. It has a lower CFM, but was much simpler and faster to put together. I tested it and as long as the extractor is directly next to whatever you're soldering, it seems to catch all the fumes.
Check out my step-by-step write-up on howchoo!
AIO Robotics PLA
I ended up plugging the internal cord hole to prevent air leakage (since I didn't have/need a front plate switch).