Smoke a cigarette or 2 or 3, place them in a plastic bag, and then bury that bag in a container such as a suitcase or backpack. From my experience it gives off a "new car/rental car" smell and lasts for quite a while. Obviously the more used cigarettes you pack the closer the smell will be to actual cigarettes. Be cautious though, my first time trying this I was taking my laptop out of my backpack in a class only a day after putting in a bag of 5. It was way too strong and I think the person near me could smell it