This reminds me of the time I took a large steel mallet (12+ lbs.) with me to high school. Few things are more priceless than the look on the secretary's face when I said: "Hello, I'm here to check my hammer."

On the topic of weaponry, I have little doubt that I could create a firebomb in an Altoids tin which could easily start a fire that could take out the whole school. (The trick is to put it near something flammable...such as the oxycetylene torches they used to keep in the art metal room).

More like 99% Fear Mongering.

Oh that brings back memories.
Kid at my HS (pre-Colombine) did a report on Feudal japan, and the teacher was handing out extra credit for props brought in, expecting innocous things like pottery, etchings, etc. This kid brought in a No-Dachi, though he did contact the campus cop prior and made the necessary arrangements.

A friend of mine did a "How to" speech on laying seige to a castle. Built a working scale model of a Trebuche (it was about a foot tall), the smart ass teacher asked him to proved the little thing worked. So he fired a small clay ball (for just this purpose) and smacked the wall behind the teacher, just above his head.

Another buddy, with a similair report, built a ballista (though he called it a cross-bow) using the leaf-spring off a VW Bug. His target was the school's old 1.5 ft thickness brick wall that was going to be torn down later that day and replaced. Fired a piece of rebar through it and handed it to the campus cop without so much as a word. He knew it would work, but nobody believed him.

Another buddy at my HS did a How-to on making nitro glycerine (yes, strange friends) but his was done as a joke. At one point in the speech, he stated something to the effect "If the mixture begins to smoke, leave the area immediately, as it is going to explode." As he is giving the speech, he has been adding things to a bowl that you can't see into, but they were all harmless mock-ups. Inside the bowl was a piece of dry ice, the last ingredient he added was some water as he stepped around the table to give the warning, and on queue, thick creepy smoke begins pouring out of the bowl. At which he runs out of the room. I just wish I could have had that class as I knew the joke (and told him about the dry-ice and water bit)

He wasn't trying to create a link for future reference. I would imagine he was figuring that anybody else looking for this would look for the original thread, which in fact had a pretty appropriate title of "Weapon Concealability, Conceal 6 my ass."

One word: Thermite.

My senior year of high school, I built a small scale model of a Roman torsion ballista for Latin class. Wasn't very big... less than a foot across, used rubber bands for the torsion skeins. It'd throw a pencil across the room, though not hard enough to really hurt. However, the Latin Club a couple years later - with the Latin teacher's full knowledge and cooperation - built a full-scale one based on my model, and took it out on the deck behind the Latin classroom and started lobbing broomsticks out across the parking lot with it. When one of the vice-principals showed up looking to bust some heads, she found the Latin Club crewing the siege engine, with the Latin teacher standing by, wearing her Roman cavalry helmet, and pointing out targets and shouting exhortations in Latin.

And my chemistry teacher senior year taught us how to make thermite and we mixed some up and set the bus parking lot on fire with it. It's pretty impressive stuff... we had about a quarter-inch in the bottom of a tuna can, and used a strip of magnesium as a fuse to set it off. As bright as magnesium burns, when it hit the thermite, it got even brighter, and there was a wave of heat that, from twenty feet away, felt like standing next to a bonfire. It was pouring rain, and the thermite flash-boiled a sizable circle of pavement dry, and lit the asphalt where it was sitting on fire, the which continued to smoulder for a while after the thermite itself burned out, until eventually the rain put it out.

Thermite is also trivially easy to make. The prices and Availabilities given in M&M are totally cracksmoking.