Sara here. This is such a great idea. I always hate wearing thick socks in my boots cause they make the boots too tight and uncomfortable. But these boot cuffs are amazing and really easy to make. Mine don't look the same because these ones are knit and I crochet, but it works.
Theirs and Mine
I used a H 5.00MM hook and grey 50% acrylic 50% wool yarn. You will also need a yarn needle and scissors.
Chain (C) 12
Double crochet (DC) in second chain from hook
DC next 9, chain 2
*Front post stitch next row, c2
dc next row, chain 2*
repeat from * till the length wraps around your upper calf tightly
Tie off the end but leave a long tail for sewing
attach a single crochet on the seam and continue with the single crochet all the way around the rim
C1 and repeat single crochet until desired length is achieved.