Spray the inside of your animal mold with with a thin layer of cooking spray.
Empty the bag of structural concrete in a wheelbarrow and add 4 pints of water per every 50 lb. bag of cement you are using. Mix up the contents with a shovel. Add additional water as needed until it is a thick, plastic-like consistency.
Scoop concrete out of the wheelbarrow with a scooper and place it in the mold. Put more concrete in the mold until it rests level with the mold's surface. Let it dry for 24 to 72 hours.
Place the mold on a solid surface with the concrete side facing down. Grip the mold and lift it up, removing the animal mold.