The ingenious design creates a diagonal which looks really cool and swirly....
...and makes the teeny tiny cast on a perfect fit on the big toe.
Some increases, some decreases, some twists, some turns and Voila!
Worked in Steam Valley Fiber's Hand Dyed Fingering Sock Yarn in Rainbow. I think a slightly longer color repeat might make the swirliness even more pronounced. 'Course this is just the half of it. You'll have to wait for the mate to get the full effect.