Oysters live on the ocean floor. Oysters have a hard outer shell, and a soft inside. Oysters are capable of making pearls inside their mouths. An oyster costume is very simple to make, and has many uses. Other than Halloween, the costume will work for plays and skits or for a live poetry reading, such as the poem, "The Walrus and the Carpenter" by Lewis Carroll.
Draw the large outline of an oyster shell onto the foam or cardboard. Make two shells. Draw the shell as if it were open. Make a round opening near the base of one of the shells for the person's head. Cut out the shells from the cardboard or foam.
Paint the shells with white spray paint. Make sure to paint all of the edges of the cardboard or foam as well as the front and back. Paint the shells with two or three coats of paint. Allow the paint to dry.
Add the details of the shells with acrylic paints and small paintbrushes. Use a picture of a real oyster to help make the details. Paint one side of each shell like the inside of the oyster mouth. You will place the shells on the costume as if the shell were open and the person's head is inside the shell.
Hot glue the shell without the hole to the front of the sweatshirt. Place the edge of the shell where it would attach to the other shell along the collar of the shirt.
Paint the costume-wearer's face with a pearly white face paint. This will help her look like a pearl. Give her a white beanie to wear on top of her head.
Have the person wearing the costume push her head and neck through the opening on the last shell piece. Position the shell so that it will not fall off easily. If necessary, add a strip of elastic to the back of the cardboard to go around the back of the head to hold the top shell in place.