Here's my little carton of milk and cookie for Halloween.
Unfortunately the cookie costume doesn't look very round when he wears it, but at least it is ultra comfortable b/c he is picky that way. I hot glued the chocolate chips on. I added pipe cleaners in the seams of all the edges that were open - arms, legs, and head. Then I sewed the other sides together. It looks round... until he puts it on! *LOL* At first I was actually pretty po'd but life goes on. Live and learn.
My daughter's carton of milk came together really well. Her hat is a spout. It was very hard to get it to fold nicely - maybe it wasn't long enough. I stapled it together on the backside and left the spout pushed out. To keep it on her head is a strip of poster board that curves upward to fit the shape of her head. Then I stapled elastic on for a strap. The carton is super simple. I used 2 pieces of poster board and folded them in 2 one big section, one medium section, and one small section (for gluing) The straps are also posterboard just stapled on. The word milk is from the Ashyln's Alphabet font by Cricut. The cow is from the Create a Critter cartridge.
Not perfect, but original enough. My daughter loves hers :)