Based on the answers provided, the following corrections need to be made to the 3D object:

1. Attach a semi-hexagonal section to the rectangle. The current attached section does not resemble a semi-hexagon and needs to be replaced.

2. Ensure that the larger edge of the semi-hexagonal section is connected to the longer edge of the rectangle. This detail was unclear in the current model.

3. Adjust the length of the semi-hexagonal section to be 2/3rd of the length of the rectangle. This proportion was not clear in the current model. 

Please note that the base shape of the object should remain a rectangle and the object should continue to be extruded in one dimension.