For a material that is so rigid when dry, plaster wrap is generally flexible material to work with. Plaster wrap can be used on its own to create dimension and texture in a piece, and it comes to life when used to alter a smooth surface.
To create a nest shape from a Styrofoam sphere, begin by cutting into the shape until you reach the center.
With scissors or a craft knife cut away about a quarter of the sphere (from the center of the sphere).
With the rounded side facing away from you, smooth the interior until it resembles the inside of a nest.
Fill a plastic container with water. Cut three 1" (3cm) strips of plaster wrap, and dip each into the water one at a time.
Place each strip one at a time on to the nest.
As you are working, cover the sides and the top of the nest. If need be, cut an additional strip, soak, and apply it to the nest.
Cut a piece of plaster wrap so it is 1" (3cm) longer than your work surface. Wet the strip and place it on the surface allowing 1⁄2" (1cm) to drape over each side.
On the top of the plaster wrap strip, place the covered nest, pushing down slightly to ensure the wrapped surface and the nest adhere to one another.
If need be, reposition the strip and/or the nest by slightly lifting on one side of the background strip.