It's so kawaii! I just made this up to go to a screening of this movie! Sorry I don't have any photos, but I lost my camera cable.
So , to make a pattern, let's start with the eyes. You take the largest coin you have, or just about a circle an inch in diameter and cut it out. Then proceed to cut that out of white felt. VERY IMPORTANT! Do not sew that on to the hat yet!
Next, you cut out the pupils out of the black felt. I traced a very small button, but you can make it whatever size you want, it's your hat! Now, line up the blacks and whites on top of each other, and sew them on where you want them.
Next, the nose. Just draw a very small, wide and short brown triangle. Feel free to sew this on. This will be his nose.
Cut out a spade and cut out the bottom out of grey felt. These will be the ears. Sew them on the top so they pop up really cutely! You can go the hard way and do two layers, and make them curl up, but I'd suggest the easy way.
If you have stronger work ethic than I do, you can also make a leaf on his head. This way, of course cut out a leaf shape and sew it on the head.