Braiding plastic ponies

"Soon I was up to starting with twenty-seven pieces (nested down to nine braids, then to three and then one) and then on to eighty-one. All the while I was learning about math: I saw that division is the process of taking a large number of things and grouping them into a smaller number of groups. In order to end up with one even braid at the end, I had to be able to divide the initial number evenly by three, then by three, and then by three again, until I ended up with just one braid."

—Christine Alvarado
and there's more at the link below

SandraDodd.com/mylittlepony
photo by Sandra Dodd, of Holly demonstrating this, years ago
(click to enlarge)