Since rocks of different shapes/colors/sizes fascinate me, I'd use 2-3 layers of medium thick rope, glue asst. (preferably sm rocks/pebbles) randomly or linear to the length size of rope you need for each tieback.You can use Liquid Nails glue b/c when I use a glue gun, eventually things just seem to come apart.
I've found small heart shaped rocks on our trips to the lake.Always collecting rocks.Mj