I think it would be cool if sometime in a update soon (not necessarily v9 if you don't want to) you made it possible to put decals on vehicles changeable by the printer. For instance, you could use the printer on the ball and have the choices of the stars, a 8 ball, a bolder like texture, a soccer ball, and none.
This would be a really cool feature, and would be great for modders. For instance, the biplane could have prints that put stars, or other nationality markings on it. The box truck could have different companies on the sides. And so on.