Download Subway Advertising Billboard Mockup Free PSD. This Subway Advertising Billboard Mockup is great for your Poster, Flyer, product, Movie Poster, presentations, advertising showcase. This is a Mockup of wall-mounted billboard in a underground station. However, to quickly give you an idea of how to edit the smart objects of the mockup, just double-click each smart object layer. A new document will open up where you can edit or add your pre-designed artwork and after you are done, just click save and your new work automatically updates in the mockup.