See the whole project at My Repo
Built the rocket launcher on my own. Started with by duplicating the cap on the car top. If I want to I can now have the car top on top of the car and the put the rocket launcher on the top of that an it will fit perfectly. Reading other people’s topics, I see they used mirror modifiers and linked duplicates. As I did with the wheels, I chose to use two array modifiers.
Edit: forgot the image