Tension and Leverage

A steel lever lying loose on a polished tabletop is an accident waiting to happen, not to mention unearned deadweight. Before retiring for the night, I marched straight to the heavy ceramic mug anchoring my tripwire. Leaning my weight onto my cinnamon cane, I tested the spring tension of the newly salvaged silver bobbie pin against my thumb. Substantial recoil. I hooked its crimped arm firmly under the taut blue thread and wedged the flat prong flush beneath the ceramic base. With a brisk snap, it locked in place like a high-tension trip-spring. Any unauthorized meddling with my line will now trigger an immediate, sharp metallic crack against the glazed pottery. Defense automated with zero extra expenditure.