Row 1: hdc in 3rd ch from hook, hdc in each ch across
Row 2: ch 2, hdc in front loop only in each st across
Rep row 2 until the boot cuffs are long enough to wrap around your calf. Sc the two sides together, without cutting yarn. I did 37 rows. I found it better to do an odd number of rows so that the two sides looked more seamless when attached.
For the shell edging:
Row 1: ch1, sc around the top, join with sl st to beg ch
Row 2: ch 1, *sc in sc, sk 2 sc, 5dc in next sc, sk 2 sc; rep from * to end across, join with st st to beg chain.
You may have to fudge the edging depending on how many rows you had, but mine worked out pretty well.
Make the second boot cuff, and fasten off and weave in all ends.
My finished boot cuffs are 5" tall and 14.5" around.