Everyone needs a place to prime their miniatures. This is the first and one of the most important steps of actually painting a miniature. In order to get a good prime you need a good location to spray it on the models. I use a cardboard box out in my garage as a mini paint booth.
I cut off the bottom flap from the top of the box. This allows me to prop open the side and top flaps or 'lock' the box shut with great ease. By putting the models in the box it helps keep the primer from going everywhere and keeps the primer more concentrated.
Once the models have been painted I take them out of the box on their tray (a piece of scrap cardboard) and let them dry on top of the box if it isn't too hot or cold. If there is a temperature problem I carry them into my hobby room in the house to dry. Since I keep the door shut most of the time so the smell isn't a problem.