I went to the courthouse with a friend (ticket), and had to go through the machine with my purse. LOL, no bells or whistles went off for me, but my friend's car key set it off. In my purse were my car keys with a swiss army knife as the keyring. If I got in with that think what else you can get in there.
I'm with everybody about the knitting needles on the planes could do more damage than a nail clippers.