2'x4' grow tent. I got some great results doing that. The thing is you either have to get one of the taller 2'x4' tents (Mars Hydro has one), or keep your plants small (LST for example) since you need at least 12" light distance when the plants are in flowering. Also make sure you're using an inline fan so you can exhaust the heat from the grow space. An air-cooled hood makes that easier.