After searching forever for sweatshirt fleece or a suitable sweatshirt to alter, I found one at Goodwill - it's darker than I'd like but it was $4, ALA was a month away, and it was right in front of me. Since Mabel's sweaters don't have ribbing around the hems, I cut off all the ribbing and re-purposed it to make the collar. I stuffed it with batting for structure and to give it that cartoonish look. I also had to take in the sides and the sleeves as the sweater was large on me. There is elastic around the cuffs and hem to give them shape.
The stars were done with freezer paper stencils, acrylic paint mixed with fabric medium, with a thin layer of sparkle fabric paint on top (I felt the whole costume looked a little bland without it). This is exactly the sort of thing I got a vinyl cutter for, but vinyl is expensive and since Mabel decorates most (if not all) of her sweaters herself, I figured a more hand-made look would be proper.
The skirt was made from milliskin spandex leftover from Bittersweet Lulu. It just so happened to be a very close color match.
Since I was making the stars sparkly, I figured the whole thing could use a little more sparkle, so I glued a bunch of rhinestones to a headband and gave some old, crappy flats a glittery makeover (black glitter is kind of lame as far as glitter goes, but I figured it would be better than just plain, flat black). I guess the headband is now the wrong color but... IT DAZZLES. I liked that I was able to think of adding these kinds of details, not only for the extra touch it brings to the costume but because it really ties into Mabel's love of crafting.