A safer idea is for people to build EMPs, since they have much less potential to be used to hurt humans compared to the heavy weapons you mention.

I don't know how effective it is, but I've heard that one way to get the high instantaneous power need for an EMP is to use a potato cannon to fire a very large cylindrical permanent magnet through a wire coiled thousands of times around the cannon barrel. I haven't seen any video proof of this idea though, so take it with a grain of salt.