A couple people have asked how to make costumes like this Blue Whale:
Below is a brief tutorial on how to pattern an object to turn it into a costume. I'll be posting several times in a row to post the whole tutorial, since I have to upload pictures. Usually I sculpt a model, but here I'm using a toy Allosaurus. This toy is about 9 inches long which is about the minimum size for this method of patterning. The larger the object, the more detail you'll get in the pattern.
Step 1: Gather tools and supplies
toy or model
wide masking tape
butcher paper or other large size paper
1/2 - 1 inch thick mattress foam (the green foam from Joann will work)
box cutter/utility knife
upholstery or automotive thread
Step 2: Decide how to fit costume on wearer
Here we're patterning a toy Allosaurus for a dinosaur costume to fit an adult. We want to line up the dinosaur arms and legs more or less with the human arms and legs. On the model, the shoulders and hips are about 2 inches apart. On the wearer, the shoulders and hips are about 18 inches apart. That means our scaled up dinosaur needs to be 9 times bigger than the model. This will make the costume almost 7 feet long - an impressive size.