ANIMAL TRAP
Blades bolt to the middle to kill, to the ends to spare.
An animal enters the tunnel-shaped housing and tilts a baited platform, which turns a tilt rod and releases the hinged plate mounted on top. Weights secured to the plate force it downward. If the blades are bolted at the central slots, they engage the animal; if the blades are moved to the outer flanges, they instead close the tunnel ends and hold the animal alive inside. A modified version substitutes helical springs for the weights.
“Furthermore, such an arrangement is adapted to be effective when different animals approach the bait from opposite ends of the trap, or from a common end, but are spaced with respect to their distance to the blade members at the center portion of the trap. In such a situation one would be killed and another trapped alive.”— Frank Roman, from the specification
And the world did not beat a path to his door.