Make a surprise RGB-LED matchbox. When you open the box the RGB-LED will switch itself on. When closed it’s turned off by the self made switch. All in all this is not a soldering challenge, just a few points to solder 😉 But it looks nice in my cupboard.
2x neodymium magnet 2mm
3mm RGB slow flash LED, 3v
cr2032 3v button battery
an (empty) matchbox
and of course a soldering iron with some solder, and other tools….
The copper tape conducts electricity from the battery to the LED. The battery has a positive and a negative side. Often the positive side is marked with a ‘+’ sign. The LED also has a positive leg (long) and negative leg (short). I use some copper tape on the inside of the outer box and the outside of the inner box to act as a switch. The battery is locked in between two neodymium magnets and some copper tape, so you can replace the battery when needed.