To make a ladybug racer, you will need half a walnut shell, paint, a marble, and a smooth board at least 46 centimeters long.
Paint the walnut shell to look like a ladybug or any other design you like.
Place one end of the board on a few books so that the board is slanted.
Put a marble under the walnut shell and let it roll down the board.
Make several racers and have contests with your friends or family, or give them as gifts.