You can select the Box from the Objects category in the Library tab. Resize it to be thicker and match the construction dimensions, and then apply a fabric material from the library directly onto your box object. If you need to customize the material properties, you will need to duplicate the library material first in the Materials category under the Design tab, then apply the duplicated material and make your adjustments.

The alternative option of exporting your build is also available through the File menu using the Export Model command, which allows you to work with the model in other 3D software like Blender for more precise cover design. You can then import the refined cover back into Capture.

Both methods will give you a professional roof cover that integrates properly with your visualisation project.