Based on the answers provided, the following corrections are needed for the 3D object:

1. Change the shape of the object from hexagonal to square. Ensure that all sides are equal and all angles are right angles to meet the characteristics of a square shape.

2. No changes are needed in terms of the object's extrusion as it is consistent across its height.

3. Adjust the proportions of the object such that the length is twice the width. This may require adjusting the extrusion dimension while maintaining the square shape.