Build a box that is bigger than the hole. Like if the hole is 4'' diameter, the size and shape of a shoebox is good.

Now paint the inside matte black.

Install a baffle down most of the length as shown.

You want to bend the light around a corner because light CAN'T bend around corners, see? You get ventilation without light leakage.

You biult a grow box you can probably figure out how to build this baffle.
stinkyattic Reviewed by stinkyattic on . Garden Knowm Hey dude...its me again...just a few questions again... 1- is there such a thing as 2 much light? i now have 2 150watt CFLs..2 100 watt CFLs and 2 75 watt CFLs...in my new grow box..*patented by me...made by my barehands*...they are over my plants by about 1-2 inches...with 2 4" fans constantly blowing on them...with on nice fan blowing outward for my ventalation..which brings me to my next question... 2-what do i use to cover the hole in my box for the ventalation fan?...i figure that your Rating: 5