the base metal(10 bars) determines what the sheild does when a monster hits it. the middle thingy or emblem( 2 bars) determines how STRONG the sheild's effect is. eg. i made a sheild with the base made of 10 copper. the emblem middle thingy is made of two plutonium. when a monster hits the sheild, it is frozen for 5 seconds. if i had used two rust for the center emblem thingy, it would only have frozen the monster for 1 second. plutonium does have an effect; it determines how strong the sheild's effect on a monster is.