There are two ways to go about this. I will discuss both.
Step 1: The Fun Way
Next color in all the areas you need.This may take some experimentation with colors. I had to find three different shades of green as well as all of the other colors.
Take a look at the last two pictures. Success?
Step 2: The Fast Way
The board was corrugated cardboard half cut through to preserve it intact yet let it bend.
Another good board material is compressed cardboard as seen in degroof's instructable.