We do that with a PNG file that is almost completely transparent. All hands still rotate from their center point. That doesn't change. but we can create an image where the "pointer" is at the edge. In the image below, the "second hand" is a full size rectangle that will still pivot from the center point, but the only artwork in the image is at the very edge at the top. When it rotates, you'll only see the edge graphic rotating at the edge of the watchface. Does that make sense?