modern city 3d model

Create a realistic 3D printable modern metropolis covering the entire area with dense development and almost no empty space. Include hundreds of skyscrapers, apartment towers, offices, hotels, shopping centers, factories, houses, roads, intersections, parking lots, parks, trees and vehicles. The city must look like a complete living city from above with varied building heights and realistic urban planning. Place normal rooftop helicopter pads on selected buildings across the city. The helipads must not form visible letters. Instead, their positions must be arranged so that connecting the centers of the helipads from a perfect top-down view reveals the hidden message "HAPPY 16TH". The city should appear completely natural while secretly containing this pattern. High detail, realistic architecture, optimized for 3D printing.