Mobile Canvas

Driving across the Bay Bridge one day, we spotted the vehicle below. It's covered with a 3-dimensional city which is a work in progress (some of the buildings are still unpainted). I'm not sure how "legal" it is (insert visual of a miniature skyscraper lodged into the windshield of a nearby vehicle), but it's neat to think of the different ways you can create a mobile canvas. It also makes me wonder what inspires this type of dedicated creativity?