A saddle‑shaped throat is the minimal surface for a pinch‑through, so it’s the most efficient shape for holding two mouths together, but that efficiency comes at a cost. The curvature is negative along one direction and positive along the other, so any perturbation grows quickly unless you’ve got exotic matter or a counter‑gravity field. In practice, you’d need to keep the throat’s radius just below the Planck scale and supply a steady flux of negative energy density to damp the instabilities. It’s a tight balance—more than a tweak, it’s a design problem that turns every micrometre of error into a catastrophic pinch‑off.