One blew up in a FedEx line one was discovered. https://www.cnn.com/2018/03/20/us/austin-explosions/index.html
I don't think bombs are illegal under US law. Which law bans their creation? Or the ownership of them? Certain types of explosives are illegal to obtain without a permit, but gunpowder is almost certainly not one of them.
You're kidding right? https://www.atf.gov/explosives/docs...ves-laws-and-regulations-atf-p-54007/download You can't even possess an M-80. https://www.atf.gov/resource-center/fact-sheet/fact-sheet-illegal-explosive-devices