Imagine the amount of electricity consumed by the millions of door bells being rung every minute around the world. Why, global warming is being accelerated immeasurably by this button-pushing cacophony. Save the planet. Make a door knocker out of a broken hockey stick!
Most manual door knockers operate under the “pendulum interrupted” principle. A mass swings on a pivot in an arc, and instead of gracefully climbing against gravity, it smashes into a door. A nice sounding board and mounting plate keep to a minimum any damage by enthusiastic salesmen.
The decision about what to use as a weight at the end of your door knocker is pretty open ended. The fact that a broken hockey stick will be your knocker arm is a given. What must be considered, however, is that you need a darned good collision of solid objects to transmit a vibration that will alert those inside to a visitor. You need something with heft. You could invoke the patron saint of unnecessary mechanisms, Rube Goldberg. Using his design philosophy, you could easily empty that hockey kit bag in the name of astounding those coming to your front door. If you are really stymied by all this, you could just leave a hockey stick by the front door with a sign: “Rap sharply to announce your presence.”