Imagine a tiny, meticulously crafted model city nestled within the hollowed-out half of a tennis ball. The cityscape is a miniature marvel, with skyscrapers made from translucent materials that glow softly from within, casting a warm, inviting light. Tiny roads wind through the city, lined with minuscule trees and delicate lampposts. In the center, a sleek, futuristic vehicle hovers above a microscopic street, its tiny lights creating a vivid contrast against the darkened backdrop. The green exterior of the tennis ball serves as a natural dome, with strands of grass peeking over the edges, blending the boundaries between the miniature world and reality. The scene is whimsical yet incredibly detailed, evoking a sense of wonder at the intricacies of this tiny, hidden metropolis.