A hands-on case study in using Claude Opus to design and ship interactive Three.js hero scenes for various case studies. Three full-viewport Three.js heroes built in one session: a hybrid 2D arcade + 3D candlestick hero for a gamified trading project (example 1), a cinematic floating diamond with orbiting tokens (example 2), and a Tron-style wireframe terrain where every market becomes landscape (example 3). No design assets, no Figma imports. I locked the design system first, specified the art direction, and iterated visuals using Claude. I drove the design. Claude handled the implementation.