My son was asked to make a model of the solar system, so we did. It took 7 miles to make a scale model. We measured in relation to the sun being 2m. wide in the middle of his playground & found objects the right diameter for each planet and took photos of them the right distance away. Walking this gave some semblance of scale. The distances and diameters of each object-planet are under the cards.
@lauraritchie I have in the back of my mind a 'discover the solar system' project for the town where I live - the Sun would be at the intersection with the highway, and the planets would be at intervals on the road through the town (and would go out the other side, because it's not that big a town).