Marbles cascade down a spiraling wooden track, weaving side to side as gravity pulls them along. The track is a single hand-authored CatmullRomCurve3 (helix, S-curves, and drops) extruded into a tube mesh, and each marble samples the curve's tangent to derive local slope for physics-like acceleration and rolling spin. A lazy chase camera lerps behind the lead marble whenever OrbitControls has been idle for a couple of seconds.