Things You'll Need
Flexible craft foam
Plastic dorsal fin
Blue or gray spray paint
Transforming a person into a dolphin is a tricky process because their body types are so different. A dolphin has a streamlined, tubular body with a tail at the end while a person has a torso with several limbs protruding from it. One effective way to overcome this dilemma is to create a suit from craft foam that looks like the body of a dolphin, which the person can then wear like a jacket. If done right, this project should take two or three days to complete.
Draw the outline of a dolphin body onto a piece of butcher paper. Make the outline long enough to cover the person who will wear the costume from over the head down to the ankles. Make the outline look like the side profile of a dolphin with a pointed top for the head. Cut out the outline.
Transfer the pattern onto a piece of flexible craft foam. Cut out two outlines. Glue the two shapes together along the long back edge where the patterns match. Allow the glue to dry overnight.
Cut two flipper patterns from the craft foam long enough to cover the costume-wearer's arms. Cut a hole in the sides of the main body of the dolphin large enough for the person to slip their arms through. Glue the dolphin fins to the top of the holes in the dolphin body.
Carve out a tail shape from the foam. Glue the tail shape to the bottom of the costume. Glue the dorsal fin to the back of the costume. Allow all glue to dry overnight.
Place the costume on the wearer. They should slip their hands through the holes in the main body of the costume and the flippers should cover their arms.
Attach one or two strings to the costume to hold it in place along the body. Use scissors to punch a hole in the costume so you can tie the string in place.
Paint the costume blue or gray and have the wearer don a white sweat suit to mimic the belly of the dolphin. Add eyes and other details to the costume to make it realistic.