Laser Beam

Initially installed to ward off rats and other vermin, laser beams have proven to be an invaluable interior design addition to an already impressive array of deadly choices.

The good thing about the laser beams is that it increases in width a little before blasting with a full (deadly) force, giving a hypothetical person, let's call them "Pizza Delivery Guy" just to pluck one from the air, a chance to avoid their deadly rays.

P.S. The rat problem never went away.