Zippo has some hardcore lobbyists! You can now bring empty Zippos on planes, at least in checked luggage that is. I’ve been following this Zippo thing pretty closely since I use a Zippo shaped camera and those aren’t allowed. The little camera has a cool mode that will take photos on a timed basis so when I travel I like to have it take time-lapse pictures out the window while I am gone. Link.
Empty Zippos OK on Planes