I read a pretty good write up on that non-gun. Everything you would need to build it, is commonly available at the hardware store. Fireworks are common in Japan, so obtaining propellant was not an issue. Electric ignition, using batteries and 0000 steel wool, a combo that is commonly used to start camp fires. I still think it was a false flag, but it wouldn't take a rocket scientist to build such a weapon. I tested the ignition system with some loose black powder, steel wool and a 9v battery. Fired off every time. You could build an explosive device using the same system.