Single massive floating sci-fi sky ...

Single massive floating sci-fi sky base with one central tall tower and clean radial rings. Use polished blackstone and deepslate as the main materials. Add amethyst and purple stained glass for energy core lighting. Include a vertical beacon beam from the center. Rings should be layered, symmetrical, and made with slabs and stairs, not random blocks. Add 8 simple arm-like extensions made of the same materials. Use sea lanterns for lighting. No terrain, no extra islands, no clutter—only the main structure, clean and detailed.