Hate to be the bearer of bad news, but I was a… shall we say precocious, child. I made a lot of bombs in my back yard lol, started when I was like 11. Illegal as fuck but really fun, only made small firecracker type stuff but all I needed to do to scale that up was math and use metal instead of cardboard, I had already learned you needed a bit of air in the tube for the mix to ignite, etc. And all of this was before the Boston Marathon bombing showed us the power of a pressure cooker from Kohls, some nails from Home Depot, and a few chemicals I won’t list here but that can be easily found online/purchased in stores. Not gonna give out recipes on lemmy though lol, just saying, it isn’t as hard as you think, and as long as you aren’t Jack Parsons you’ll be ok.
(Warning: do not attempt at home, I am not responsible for your mistakes or actions, nor the government’s in arresting you for this illegal shit. And it goes without saying but if you do look any of this shit up, don’t use it to harm stuff, even “for the greater good,” just have fun with small booms, they’re fun enough on their own! Science!)