What you need:
12 yards of pink tulle
Pale-pink or white leotard
16 by 20-inch white oak tag or a craft-foam sheet
Elastic measured to fit under chin
To attach tulle to the leotard: Make a loop in the tulle every foot or so, twist the loop, and then glue to the leotard at the twist. Don't worry about perfection: Loose, lumpy, and bumpy is what cotton candy looks like!
For the hat, roll a paper cone out of white oak tag or a craft-foam sheet; glue; punch holes in the sides and thread elastic through, knotting the ends, to make the chin strap.