Hey, Guy? If I could make a miniature gun that was 1.7" long and contained no moving parts and could still fire bullets, I could also make it in shapes other than gun. If your security seriously contemplates defending against that level of technology (firing bullets out of a solid object less than 2" long), then you'd better confiscate all metal objects, period. Also, what are you doing about other conceivable -- but technically impossible -- threats, like telekinesis, voodoo, and directed sunspot radiation? Link
"How do you know it wasn't a real gun?" asked Guy, a security agent with the Canadian Air Transport Security Authority, who also declined to provide his last name.
"Who knows if there is a gun that small that can shoot bullets? You don't know that. They followed the rules."
I write books. My latest is a YA science fiction novel called Homeland (it's the sequel to Little Brother). More books: Rapture of the Nerds (a novel, with Charlie Stross); With a Little Help (short stories); and The Great Big Beautiful Tomorrow (novella and nonfic). I speak all over the place and I tweet and tumble, too.