Bottle Stopper LED String Lights
They are easy to install and look great, and since they are battery-powered, there is no hassle with electrical cords. The small bulbs, closely spaced only 2″ apart, radiate an intensely bright glow.
They fit into most any shape of bottle such as wine bottles, champagne bottles, liquor bottles, beer bottles, etc. without the need to drill holes in them. Fits for most standard wine bottles with openings from 5/8″ up to less than 7/8″.
Just drop the 3 ft string of 20 tiny lights inside an empty wine or liquor bottle, arrange as desired, and slip the battery compartment into the neck. The slide switch on top of unit turns lights on and off.