This is sweet. Great little cab built on the cheap. I'm just wondering about 2 things:

1.) the clear bottles (as previously mentioned)...roots are much better off in the dark.

2.) The ventilation. You say you've got a fan exhausting the cab? Passively? i've never heard of a passive exhaust...passive intake, sure.

From your description (...1 blower exhausting, passively...My hinging door stays shut perfectly just by the suction...) i am willing to bet that you could improve your ventilation by adding a passive intake. The fact that the door is being held shut by suction says that there is an imbalance in airflow. Your fan is more than likely not running at it's full potential because it isn't able to pull new air in. Cut one or two 4" holes near the bottom of the box. Your door will probably need to be tacked shut, but i bet your fan works a lot better and your temps may even go down a bit thanks to the even exchange of air.

lookin good though. keep it up.
Skeet