I like to use clear sprue for this because you can see if there are any bubbles inside. Cut through the bubble and you will have a centered pilot hole for the rest of the process. If there aren't any bubbles, use any sprue handy. Just cut is flat and carefully drill a hole centered on the end. Choose a piece that is close in size to the hole in the wing or fuselage you need to fill.
Make the end concave with a drill bit the same size as the sprue. Drill the center hole a little deeper if necessary. You want about an 1/8" after the end is drilled out.
Press a small piece of chrome Bare Metal Foil into the recess using a Q-Tip. Give it a little twist as you push to get it smooth and polished at the same time. Trim the excess foil away with a very fine sanding stick lightly pulled along the edge. Poke a hole in the foil in the center.
To make the bulb, stretch some clear sprue so it will fit in the center hole. Point the end of the sprue at a candle flame and move it slowly closer until the end start to round over. Cut off the "bulb" and glue it in the hole in the bottom of the recess. Highlight the bulb with a tiny drop of a thin black wash. After that dries, make is sparkle a little with a drop of Future.
WARNING! The next step involves the use of an open flame. Use extreme care. Plastic will ignite quickly. Melted plastic will stick to the skin and cause serious burns. Due to the extremely volatile nature of many of the things we use in our hobby I strongly urge you to do this away from the workbench. If you are a youngster... get the help of an adult. If you are an oldster... then you should know better and be careful! If you think you are ready to go... READ THIS AGAIN!
Cut the lights to the desired length and glue in place so they just below the lens. If you have a punch set, cut a new lens from clear sheet styrene, dip it in Future and let that dry before installing over the light. If you have to use the kit clear part, it can be sanded thinner, polished and Dipped in Future to make it clearer.