Idea for I map I want to make

[a_marine]

I'm gonna try and make a map that is kinda a cross between 343GS and AotCR. The AotCR base would have a lot of rooms and elevators to get higher and a giant tower and would b the Blue base. The 343GS part would have elevators and rooms getting lower with a big structure at the bottom and would be the Red base. The flags would be at the top of both structures. To get in between them there would be a giant door. What do you think? Also I would need to know how to make rooms in walls and rooms and elevators going down.