I can't remember how many stitches I cast on, but I basically followed the Fibonacci sequence for the increases, as well as increases on both edges on every right side row. I will get around to writing it into a pattern and load the PDF.
I used two Magic Balls, a little bit more mohair and also a very small amount of Manos wool. You could, in theory, use any aran-weight yarn but I like using mohair for stuff like this. The fuzziness reminds me of the season, for some reason, and the yarn I used is beautifully soft.