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

1. Add two rectangular holes to the object. The absence of these holes is causing the answers to questions 2, 3, 4, and 5 to be either "No" or "Unclear."

2. Ensure that these holes are symmetrically positioned on the object. This will address the uncertainty in question 3.

3. The size of the holes should be slightly less than half the size of the original rectangle. This will make the answer to question 4 a "Yes."

4. Position the holes such that they do not touch each other or any edge of the original rectangle. This will correct the issue identified in question 5.