I'm working on a figure that involves replacing a body part with a prop. Once I've done this, I want to reshape the new body part slightly with a magnet. But when I add the magnet, it has no effect. Any clues as to what's going wrong? Incidentally, if I reshape the prop with a magnet before using it to replace the body part, it loses its new shape as soon as the replacement occurs. The original magnet dissociates itself from anything in the scene.