Heres is a cool do it your self bow

This is what what scares me we have elastics that our ancestors couldn't have dreamed of that can achieve the same results as the catapults and other weapons of war that took a long time to make and were very heavy. A few examples: these could all be use to lob fire bombs and other objects from a secured area like behind another house out of you line of fire.
Fire bombing I think would be the hardest to defend against.

With a little engineering you could turn this into another dangerous weapon.

This guy has a lot of great ideals that could be expanded upon. Be sure to check out " his slingshot channel"