You can create dimensional bulk with cardboard by cutting out shapes and gluing together stacks of your cardboard cutouts. Then cover the armature with Apoxie Sculpt, ClayShay, paperclay or paper mache clay and add texture, embellishments and/or paint.
STEP ONE: Start with an outline drawing of the piece you have in mind (here, a Cubist cat) and cut three of each of the template pieces out of cardboard.
STEP TWO: Trace and cut the template pieces out of cardboard.
STEP THREE: Stack and glue the pieces together with white glue, hot glue or rubber cement.
STEP FOUR: Let your fully dimensional, free-standing cardboard cat dry.
STEP FIVE: Cover the cardboard with the clay of your choice (red resin clay is used here), and stamp a texture into the surface before it starts to harden.
STEP SIX: Add embellishments while clay is still pliable.
STEP SEVEN: Glaze or stain if desired, and add additional embellishments (like a crocheted collar) if you want.