Bottle cap holder

Basic idea was to create a bottle cap that would fit any soda bottle. Just take off your regular cap and screw this one on instead. It has a flat plate with a hole on top so you can clip a carabiner on and clip the bottle to your belt, or anywhere else. It could also be used for tying the bottle to anything, say for 2 liter bottles on camping trips canoeing trips. or turn bottles into easy to attach weights?