Unless there's a real result kosh was after as his question was answered in the subject matter he quoted... i'm gonna ask Lady Command to step in.
I don't see any need to lock it.
If I saw a kid with a device like that, I would not walk over and ask if there was any liquid in it.
Normally you can see if there is liquid in it.
Oh and Kosh, i'd rather not get into a discussion of how 'complete' the imaginary explosive device was as it has no bearing on the end result or the motivation behind said actions. Also who would dismiss PLASTIC as a modern carriage medium?
I wasn't dismissing plastic itself, I was dismissing small and empty mostly. Steel>plastic when it comes to holding compressed gasses of any kind. I also dismissed the idea that we should treat an 11 year old as a terrorist. Baghdad != a well off middle school in california.
I see quite a few bomb attempts in that list. And I'm almost sure that list isn't comprehensive.
Looking at the list there were 5-6 or so actual bomb attacks on schools in the US in the last 50 years, and half of them were in tandem with school shootings (like columbine). Of the foiled plots, only 2 of these involved bombs and also involved not only lots of bombs but one or more guns as well. Based on this, if a kid is going to make a bomb, likely it's either a big one or lots and lots of little ones combined with guns. I'm not seeing any precedent for a kid making one small bomb at all in the US. Odds are far more likely that you'll be shot or stabbed at school that blown to bits.
It's better than nothing, but backs up the point that the only place i can find an image of the component is in a landmine. So A non-expert is right to be weary. 3rd pic down (the small white cylinder and bar contact) if you imagine the bottle as being empty with the bar most likely inside instead then you'd have a rough idea.
http://www.nolandmines.com/minestype72ap.htm
That is a good point, but how easy is it to get that kind of solid explosive in the US? In all the school incidents in the US, I don't recall seeing one that involved second hand military grade munitions.........
EDIT: I'll even quote the two bomb related foiled plots in the US:
17-year-old Joshua Magee was arrested in the parking lot of Malcolm High School after a school staff member, who saw the youth drinking liquor and putting on a black overcoat, called police. A search of Magee's car produced a bolt-action rifle, 20 bombs and a note stating the he wanted to injure everyone at the school except for three friends. Magee, to whom school paid close attention after it was reported to faculty that he was experimenting with explosives at home, was charged with attempted murder.[410]
Jeremy Getman, 18, planned a school attack at Southside High School but it was foiled after students told a teacher that he was carrying weapons. He carried 14 pipe bombs, three smaller bombs, a propane tank, a sawed-off shotgun, and a .22 caliber pistol into the school by a duffel bag and also a book bag full of ammunition. On December 17, 2001, he was sentenced to 8 1/2 years.[409]
As for the ones that happened, there was a bombing in 1970 at a university, a bombing at a secondary school in san mateo (when they searched they found a bunch of other bombs he brought to school), columbine, a bombing at a hostage crisis in 1986 in wyoming, and a bombing in Bath, Michigan in 1927. That's it.