yeah man, i had to cut holes. When i got mine, it only came with one single flange, how stupid huh. So i had to go to HD and get some flanges. I cut mine to install my 1khps that is just an air cooled hood, no cxool tube.
http://boards.cannabis.com/indoor-gr...ak47-grow.html

there are some pics and the onle i uploaded you can see. The top is a 6" hole i cut.

I would recommend to install the phlanges where you like them, then, while inplace use a razor blade and cut around the inside of the flange, it will leave you a nice circle. Super easy to install. If you have another set of hands available, you could say it's "too easy!"

But, if i were you, i wouldn't buy a HH, I'd just frame one up myslef. I guess the HH is good if you are renting or need it to be portable.

The cardboard is to keep light away from the flap at the bottom.

any other questions, hit me up.