I did it once in a forum discussion, mentioned some extremely straightforward thing that would probably take out a city. I thought it was obvious, but the replies I got indicated that nobody else understood it. I realized that if I was to explain the details, then I’d be putting out information that was clearly not obvious. And that if anyone ever did it I’d be wondering for the rest of my life if I was partly responsible.

So now I only discuss such things with people I actually know IRL.

One of them argued that in fact the simplest nuclear weapon (assuming one has suitably enriched plutonium) is to rent out a whole floor of an office block, remove all the internal partitions, lay a pipe diagonally across the middle, separate your fissile material into two sub-critical masses, put them into opposite ends of the tube, pack the ends behind the fissile material with cordite, or blasting caps, or whatever. He said you’d get a lot of fizzling and very little efficiency, but it would go “boom”.

Using a skyscraper allows you to get the height to most efficiently use you tiny explosion.

I think he said that would only work with plutonium as well.

Every day I thank God he uses his powers for good, and not evil.