Baoding balls — hollow iron spheres, usually sold in pairs, designed to be rotated in the palm as a meditative and dexterity exercise — have been made in this city since the Ming dynasty and remain one of its defining exports. The city centre around the South Market (南大街) has several shops dedicated to them, ranging from simple unpainted iron spheres to elaborate examples with painted enamel interiors that chime musically when rotated.
The craft of making them is genuinely demanding — the hollow construction, the internal chime ball, and the precisely matched weight require skilled metalwork — and the better shops will demonstrate the full range before you buy. Prices vary enormously by quality; a decent pair for actual use costs considerably less than the decorative gift versions with presentation boxes. Learning to rotate them smoothly takes more practice than watching an expert suggests.