Weapons designed for everyone are a decisive advantage at war. International experts test the three most important weapons that can be learned very quickly. The crossbow transforms peasants into warriors that suddenly become a threat to the knight. Learning to use a pike is easy, but requires bravery. The Kalashnikov is, due to its rare simplicity, considered the world’s deadliest weapon ever existed. If 3D printed guns go into mass production, it will have a large impact on the future peace.