This hat leap-frogged the Dutch hat I'm working on (ear flaps, double-knit - one prototype done but not blogworthy ... my valiant husband was even willing to wear it on a ski trip but I spared him the indignity!)
So ... I used size US 2.0 circs (2.75 mm) for this, the third model. It's just slightly too small. I should have used 3.0 mm at the very least. As you can see, it's stretched a bit to straining because it's just that tiny bit too tight.
I've altered instructions in the pattern, suggesting 3.0 mm circs and a gauge of approx. 21 stitches = 4 inches to make the bottom edge work out to about 22.5 inches when done. (My version is 22 inches and just a tad too snug.)
This hat has everything! Polar bears, leaping stags, pine trees, snow flakes, folk art roosters, and of course, matryoshka dolls! Not for the faint of heart. Mostly it's a two color process, but at some hair-raising junctures, you can be juggling 4 strands of yarn. Definitely doable, just takes patience. This is an easy enough pattern, straight-up stocking stitch on circular needles, but cannot be rushed.
And for the curious, here's a sneak peak at the first version of the Dutch hat. That's supposed to be windmills and wooden shoes. Back to the drawing board!!