My daughter wanted to be "Max the King" from "Where the Wild Things Are". I could not find a costume anywhere so I had to whip it together. She already had a hoodie with faux fur inside so we just flipped it inside out. We flipped her tan sweat pants inside out. For a tail, we tore off a long piece of fabric from an old tan shirt & pinned it to the back. The crown was roughly cut out from card board & my daughter colored it to her liking with crayons. We roughly laced the back of the crown with shoe strings so it would fit over hoodie & head. Then she needed "Max the King's" staff, so we found a stick outdoors & smoothed out the ends to be safe. Then roughly cut a paper cup to match the crown & poked it through the bottom of cup to sit on top of the stick. We added some tape to secure cup & stick. For a playful touch, we used a dark eye liner to make whiskers & animal nose.
This "Max the King" costume was a group effort. All the kids jumped in for their little sister. People in public fell in love with the costume & quickly recognized who she was which was exciting for my daughter.