Form a wooden base for the tusk to be built on. A 2-foot square piece of pine would suit well for this purpose. Drill a hole into the pinewood base of about 1 inch in diameter. Purchase a round piece of wood to serve as the bottom half of the tusk. Cut off a piece of wooden dowel 1 inch in diameter and about 2 feet high. Insert the wooden dowel into the hole in the pine wood base and glue it into place with white school glue.
Mold the base of the tusk with white modeling clay. Around the base of the wooden pole. Work together several layers of clay and work your way up the pole. Create a broad base at the bottom that gradually becomes thinner near the top.
Mix together in a large bowl plaster of Paris mix and water. Use old white clothes from old t-shirts and other rags to cut into strips and dip into the plaster. Begin to work these in circular fashion around the clay base of the tusk. Bend the clay as you desire as you reach the end and solidify this bent position with the plaster and cloth.
Allow your tusk to dry naturally or place it in front of a small fan. After the plaster has completely dried cover the entire tusk with a coat or two of white paint. Paint the base of the tusk black or another contrasting color as you so desire.