Additional

It's inevitable. Someone at your event is going to want to have a smoke. Rather than have them snuff their butts out on a dessert plate or toss them on the ground, why not be prepared with a few ashtrays? You're not going to convince anyone to stop smoking and it just wouldn't be polite to ban them to a smoking spot 50 yards from your event tent, so give your smoking friends the ashtrays they need to at least engage in their filthy habits in a civilized manner.