This was our youngest daughter's first Halloween where she was old enough to understand what was going on and to fully participate so we really wanted her costume to be special. We Decided on Boo from Monster's Inc.
It was a good choice for her for a number of reasons: she was the right age to pull it off, it's an iconic character that people recognize, and it's really two costumes in one. Under the purple monster costume we dressed her in the pink nightshirt, purple leggings and white shoes that Boo is wearing when she's first seen in the movie. This gave us an option if she got too hot or tired and wanted out of the monster costume. We could still say she was dressed as Boo!
The purple monster a deceptively simple looking costume. We did a lot of research into the film and the official, Disney walk-around character and other attempts at the costume and concluded that there were really two major elements that determined the success of this costume: the shape of the head and the fabric choice.
For the monster head, we needed something that was significantly larger than our daughter's head. It also had to be light-weight, comfortable and easy to secure so it would stay in place. We experimented with a number of options. Much to my wife's chagrin, the best choice ended up being a pair of her plastic mixing bowls. We cut a hole in one so it could rest on her shoulders and then to the second attached a child-sized baseball cap (brim removed) with a chin strap so it would stay in place. Finally the two were help together with glue and into a clamshell shape to make the monster's mouth. It worked very well but was still a little odd feeling for Misha so we quickly attached some scrap fabric to the base so she could wear the mockup playing around the house to get used to it. We found that playing her with pieces of fortune cookies worked well to get used to, and enjoy wearing the rig.
While Misha was getting used to the structure, we turned our attention to the outer fabrics of the monster. We looked all over for the purple fabric with a fish scale pattern on it and came up blank so we ended up making our own with a stencil and fabric paint. This was quilted slightly before attaching it to the head piece to give it a little more puff. We were much luckier with the tentacles, and found a great fabric with a pattern of dimensional puffs, which looked fantastic.
The other elements came together pretty quickly. The mop hair was a couple of mop heads (duh) and for the eyes we went with a pair of styrofoam balls on the end of semi-flexible, pvc pipe which we then wrapped in grey felt and gaff tape. These were secured to the head piece by drilling a couple of pipe fittings into the top of the bowl.
Lastly we glued some black felt to the inside of the bowls and attached for craft-foam teeth and that was that. It was a little awkward to walk around in at first but with practice, she did great!