The developed blank and finished cover are different dimensions

A fictional sheet-metal task supplies a finished cover dimension and a separate bending model. The learner adds the outside arc length for every bend without checking the stated neutral-axis convention, then omits the seam allowance. The proposed assembly also joins dissimilar metals in a wet exposure and fixes a long run rigidly at every point. Its visible upper face looks neat, but the concealed drainage interface has not been inspected. No cutting, bending or installation occurs here. Identify the independent geometry, compatibility, movement and water-management questions that remain, and explain why a clean-looking finished cover does not establish that the complete architectural assembly is suitable.