Lloyd E. Sponenburgh writes:

I have a Plano Gun Guard lockable case.

Last time I did that post 9/11, I used a lockable cash box inside a
corrugated carton that I taped up after the check-in inspection, on the
theory that it is less of a theft target if the package appears non-
descript and unlocked.

Once pre-9/11 I inadvertently walked through security with a loaded
magazine in my jacket pocket. The guys were amused, let me have the
empty magazine back, and kept the ammo for themselves.

I also remember in those days how after the last flight departed at
night on a given terminal wing, they shut down the security scanners and
let anybody and everybody freely walk in and out without so much as an
attendant watching. A terrorist team could have hidden an arsenal
inside the sterile area back then.

Flying out of Belize to Miami a few years ago, I inadvertently walked
through the scanner with the world's largest Swiss Army knife in my
pocket. I handed it over. I was very upset about this expensive
forfeit, not mention the sentimental value of this personal tool I had
carried for decades. A few minutes later the 3rd-world official caught
up to me and quietly slipped it back in my hand on the way to the gate
out of sight of the crowd. It was a nervous ride home for me carrying
that thing in the cabin. But if anyone needed a bottle uncorked, a pipe
reamed, or a fish scaled, I was ready.