Based on the answers provided, the only correction needed for the 3D object is to adjust the base of the object to be square instead of rectangular. This will ensure that the length and width of the base are equal, making it a square shape. All other aspects of the object, including the semi-circle attached to the top, the flat side of the semi-circle being attached to the top of the base, and the entire sketch being extruded, are correct and should remain unchanged.