Closet Odor control

Okay, Currently i got 4 plants goin in the closet. At best after sexing i'll have three. I need some odor control but anything cutting into the walls or the like wont work, besides ventillation is fine.

Is there anything (Preferbly cheap) that can be easy odor control for such a small amount of plants? I dont want to buy air freshners as chances are they will just cover the smell.

I had the same problem where I live. Instead of cutting a hole in a wall, try to find a replacement door. Use the replacement door (mine was $26) and cut you intake low and your exhaust high. On the exhaust, attach a carbon scruffer. Also, use weather stripping around the entire door. Your odor smell should be non exisitent now :)