This yarn is very slightly heavier than tosh sock, so I went from 140 to 136.

I decided not to do tubular cast on this time, because I dislike the way the twisted edge stitches look in 2x2 tubular. Since the edge of this hat is already very large and stretchy, binding was minimal risk, so I knit on the stitches, which also eliminates the second thread of long tail or tubular cast on - the yarn is so variegated that the second color created a substantial contrast between stitches. I used 3mm straight needles to cast on, though, to make sure the stitches weren’t too small, before switching to 2.25 for the ribbing.