After ordering in the parts that I need for the electronics to control the rover, I measured their dimensions and used this to plan the size of the Rover. Aside from fitting all the components, I need to be able to access the Pi and the battery pack to recharge and reboot the rover.
I intend to use plastics for the casing, and have identified 2mm thick PVC as being a good option, as it has a high mechanical and tensile strength for the price. The structure will likely be held together with 3mm threaded steel rods that have nuts supporting the plastic platforms.
The structure will be then hidden underneath the ‘solar’ panels, which are for aesthetic purposes only.