Fnord wrote:
My money is on the perp being a disgruntled ex-employee, a shoplifter who got caught, a customer who felt she was treated badly at the store, or just some random nutter off the street.
Low-tech devices made of common materials don't require any special knowledge or training, and instructions to build them are practically
everywhere on the Internet.
Why, I just read a few posts on a popular website describing how to build a soda-bottle bomb. If only I could remember which website that was ...

Oh, heck. It's still possible to find instructions for creating a 'dirty bomb' the same way the Radioactive Boy Scout did some years back. Although technically he was just tying to make a breeder reactor, not a bomb.
So, yeah. There are videos on building everything from lye-aluminum bombs to railguns. Lotta careless nuts out there. One set that is fascinating is a guy who keeps building amateur explosive devices despite losing his hand to them. It's like he just can't learn. He'll be putting one together and you as the viewer can't help but think, "um, if you don't have that sodium sealed absolutely perfectly, you'll lose your other hand long before you try to detonate it remotely with that there sniper rifle".
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