Well, I built 2 of them and they work great.
I changed some things from this tutorial but the basic concepts is the same.
I chose to use a 90* elbow on one end of each of my tubes.
Also, I used "all system chord sets" because I felt like the lamp needed more support, I also wanted the extra reach inside the tube the lamp holder for the all system chord set provides.
Finally I am cooling mine is series (one after the other) from a single 4" squirrel cage fan that has I think 230 CFM.
Temps inside my box dropeed by over 13 degrees f.
Here are some pics of the finished product.
By the way, each of my cool tubes is sporting a 400w HPS lamp.
PM me if you want any specific details.
