I would paint the undersides of the turrets first, so flip it over upside down and spray with a light gray cheap paint the undersides of the shelves a...
Make a play castle or build a storage container for Skylanders in a tower that looks like the portal. Here are my plans along the way as I built my son's. You can also learn how to paint wood to make it look like stone or concrete. The next step will show what all materials you will need.
Step 1: Materials
You will need some scrap wood (pallets for the thin side pieces and 1/4 inch plywood for the shelves and 2 foot section of a 1 by 6 to make the top, also about 2 feet of a 1 by 2). You will also need: Hand Saws (a band Saw would make it faster), Jig Saw, Clamps (lots), Wood Glue, Rulers, Pencils, a Square, Sand paper, Paint and Paint Brushes (and maybe a toothbrush). The paint I used was 2 cheap cans of Flat light gray spray paint, and small craft paint (also cheap) of a med gray, a dark gray, a black, and a dark brown. (but you could use other colors, I was trying to make it look like stone).