The idea with paint booths is to keep the dust and particles away from the painted furniture, but without creating a tight seal. Think of it like a house with a few leaks here and there, as opposed to a submarine where everything is airtight. The less air that gets in, the longer it takes for your paint to dry. Eventually, the paint will dry and seal itself. But in the meantime, you have to allow some airflow so the paint can dry. There are a few ways to do this, including a fan and a small air circulation system.