It looks like a neat technique, it just doesn't feel very self-assembly or even robotic to me. Maybe there is just not enough information in the article about w

It looks like a neat technique, it just doesn't feel very self-assembly or even robotic to me. Maybe there is just not enough information in the article about what is really going on. Like what happens when one of the things turns into an "U" to wrap the item to move. Is there a magnet shaped like an U in the background? Or something more clever?