Take the large cutout, and choose a larger hole on the outer edge of the ring. Thread a long (for example, 3 ft.) piece of string through that hole, as well as the same-sized hole directly beneath, closer to the interior of the ring.
Take the small-oval-shaped ring, and thread the same piece of string through its centre. Finally, thread the string through the large holes directly opposite to the first and second holes you threaded. Do not yet tie a knot.
Repeat the same process with the remaining large holes on the large ring. Be sure to thread the string through the small ovular ring. Once you are done, lift the mobile by the small ovular ring (see the image below).
Adjust the length of the strings as desired, and tie a knot at the ends when you are ready to move to the next step.
Finally, cut pieces of string to hang all of the elephant and heart cutouts to complete your mobile.