I spent two weekends and a few hours during the week on this. I read through the script a few times and drew out a sketch of my design. My original design didn't have the girl in the red dress but as I kept working on it, it became obvious she needed to be front and center. I wanted Cobb and Saito's heads melded to convey that Cobb is in Saito's mind. The bullet train speeding downward also gives the idea of them dropping deeper into the dream world. If you don't get any of that from it that's alright. I just wanted it to be similar to a Drew Struzan movie poster; at least as close as I will ever come to it.
I made a few more tweaks and changed the front end of the train after watching the movie again. I don't like the shape of this train's front end but that is the accurate look so I had to change it.