I made a 2-tier cake, all vanilla, the top 6" and the bottom 8". I covered both in blue fondant and stacked them. The birthday theme was red, blue, and white so I stuck to this as much as I could.
The top tier resembled the air, so I cut out pieces of colored fondant to make planes, one pulling a banner saying "2". The other sides of the top tier had helicopters.
The bottom tier resembled the ground, so I lined the bottom of it with candy pebbled, and made fondant cars. As the mother requested, I made a stop sign with her son's name in it.
I wanted to make train tracks running around the edge of the cake, so I used shoelace licorice to create tracks.
I piped clouds on top, since this is where the candles were going