When creating a child's costume, safety is always a consideration. Avoid hanging boxes or cardboard from the neck. Use the shoulders or back instead. With much younger children, it is best to keep details on costumes to a minimum to avoid the possibility of choking on stray or mishandled small objects. Also use spray paints that are child-safe. While the oyster costume does not fall under "National Geographic's" top 10 Halloween costumes for 2010, it is an easy and fun costume to make
Cut the large piece of cardboard, so that it will hover about a foot above the child's head and hang just above the knees. The shape should resemble that of a lima bean or an oyster shell.
After shaping the large piece of cardboard, cut a large enough hole in the top half, so the child can slip his head through the opening. Spray paint this outer layer of the shell with the dark grey colour.
Cut the medium-sized piece of cardboard into the same shape as the large piece, only make it smaller. It should be small enough so as not to cover the hole for the head. Glue this piece to the large piece of cardboard. It is as if you are creating the layers of an oyster shell. Spray paint this piece with the medium-grey colour.
Repeat step 3 with the small piece of cardboard. Spray paint this layer with the light-grey colour.
When the paint on the cardboard dries, glue the medium layer to the outer shell (large piece of cardboard). Then glue the inner layer on top of the medium layer.
Dot the cardboard layers with sand-coloured spray paint to mottle the shell. Glue bits of moss and seaweed around the outer rim of the shell.
Cut two small holes on the right side of the outer shell (large piece of cardboard). Knot the rope at one end; then run it through the top hole. Allow enough rope to form a strap around the child's shoulder. Run the other end of the rope through the bottom hole. Knot the rope to secure it to the cardboard layer. Repeat on the left side. The shell should hang like a backpack, only leaning against the child's chest.
Slip the white swim cap on the child's head. The cap represents the pearl.
You can also create a white mask for the child's face to represent the pearl if the swim cap becomes uncomfortable.
Make sure to cut the large piece of cardboard, so it does not hinder the movement of the child's legs.