Step 2: Prep for fitting
line you already sewed as the middle and flatten it out, the line you sewed
is the back. So match the the top of the sewed part to the front and sew
a loop, then fold the two other sides equally and loop it again and end it.
Now you have four corner thingies that are even. Real beanies have like 6-8
sewn curves. Four is fast and easier.