I live in a small apartment, and despite me liking the smell of marijuana, the scent of my -barely two week old- plant was already starting to take over my entire place. It was time then to get an upgrade, so I got a grow box which is now located in my surprisingly spacious laundry area by my kitchen.
I added a small extractor fan on top of the box and its corresponding venting duct which leads the air outside the window (see photo). In order to optimize air flow and facilitate the air extraction, I left two openings on two bottom walls of the box, so that air goes in, it gets heated up, rises, takes the smell with it and leaves the box. It has worked out perfectly so far.
One of the photos shows the plants outside, on my balcony, that's because I decided to take them out every once in a while -if it's not raining- for about 4 hours, just so they get some real sunshine. I've been watering my plant every two or three days, adding nutrients only once in a while and at a lower dosage than what's been recommended. The photoperiod has been kept at 18h light and 6h dark.