Above shows the front of the turret. The hole in the middle is where the barrel will be inserted.
Add the side and back walls of the turret.
Layer with red construction paper.
Next, roll a piece of construction paper to the diameter of the hole, and insert it.
Above shows withe turret with construction paper added to the sides and rear walls.
Above is another angle of the turret walls colored. Note, on the corners of each wall are a piece of square cardboard. This is to ensure the turret maintains its square shape and does not wobble. Cap off the top of the turret with red construction paper to complete.