You can put this solution on YOUR website! Get a large regularly shaped container, such as a right circular cylinder or a rectangular solid. Make sure it is large enough that your irregular shape fits inside with plenty of room to spare. Fill the container with water so that the water is slightly deeper than the maximum vertical dimension of your irregular shape. Mark the position of the surface of the water. Then immerse your shape completely and mark the new position of the surface of the water. Calculate the volume using the surface area of the water times the distance the water rose when you immersed your object.