Because these horses seem to be very popular, we have found that about a foot and a half of 3/32 inch wire rope works really well for attaching the pony to the rings. It is too easy to cut through strings or other easier to find materials, but if you find something else that works, let us know! You will also need two 3/32" ferrules to form the rings at the ends of the rope. We have found that a hammer works pretty well to fix the ferrules on the rope, but if you have a swaging tool, it might work better.
Make a loop with the wire rope around the horse tight enough so that the rope can't be slipped off (this has to be pretty tight!) and place one ferrule over the rope ends to connect them. Hammer the ferrule so it grabs the rope tightly. I like to attach the rope to the horse before I even leave the house - it saves time out on the curb. A kneepad would probably also be a handy item. We have been considering putting together a kit that has a horse with a cable attached plus an extra ferrule, so it would be very easy to install your own pony. Please let us know if that would be something you would like to see.