Step 3: Magnet
Take your magnet and push it into the Sugru approximately in the center. You want the edge to almost become flush with the Sugru, having it stick out the slightest amount. You want it like this so that the entire surface of the magnet can grasp onto whatever you need hanging.
You now can spread out the edges of the Sugru and even it out so that it's got a consistent thickness throughout. All of this should be done in a timely manner, as Sugru has a 30 minute work period after it's opened.