I wanted interior lighting without rewiring my passenger cars. Its easy to do with cheap parts. The two main parts are led light and a 3v cr2032 lithium battery. The LED leads can be taped to the battery. In my pictures I used a neodymium magnet to attach the light to the roof. In the First picture 1. neodymium magnet 2. battery 3v cr2032 3. 10mm LED white diffused. The last picture not really good I'm going to try to get a picture of the passenger car outside.