[pasabagi]

I'm not much of a chemist, but I don't think bombs are particularly easy to build. I do a bit of metal plate etching, and I've found multiple times that useful chemicals (specifically nitric acid and hydrogen peroxide) are pretty tricky to get hold of, because assholes use them to make bombs.

I had a friend who was making black powder as a schoolkid, and he actually had the police turning up at his house to ask questions about his purchasing history - which is a small sample, but it fits with the basic intuition about how you'd stop people from building bombs: make non-household bomb-making stuff impossible to get hold as a private individual, then just monitor people that make weird purchases of the chemicals that remain.