1kg-10kg copper sphere. Apparently it'll get you laid too https://www.kickstarter.com/projects/trancemetals/trance-sphere-oligodynamic-copper
there are many cannons laying around somewhere, just bring the sphere and some dry powder, good nuf to make some sound. wear bullets proof and helmet please :lol:
High premium organic free range GM-free potato spheres harvested with love by carbon neutral environmentally conscious 3rd world backpackers rescued from shelters.