The 'E' flag is entity, it allows you too spawn props.And Rictalspace gave some kcabdeef about CWU props, if you'd have to craft props, the E flag will be removed.
Hey you could add crafting for like seats that you can actually click e on to sit down. Also you would have to make like dark matter really rare (If that is used for pulse rifle rounds) And any rescource that is for weapons and yeah this is a very nice idea.Welcome to CG