Make simple light up buildings with LEDs and paper.
Coin cell batteries
Step 1: Decorate Your Paper Building
Step 2: Add LEDs
FIRST make sure the number of LEDs you want to use will work with the battery by pinching all of the LEDs onto the battery, positive leg on + side, negative leg on - side. Some colors require more voltage than others and will suck away all of the power so do some tests first. Add your LEDs by poking them through the paper from the front side. If you find their legs are bending too much from the force of poking them through use a pencil or thumb tack to pre-make a hole. Make sure you face the positive legs and negative legs the same direction, this will make wiring the circuit easier. (HINT: the long leg on the LED is positive and the short is negative. You can mark the positive leg with a sharpie so that you can easily tell)
Step 3: Add Copper Tape
Add a line of copper tape so that you can tape the positive legs of the LEDs to it easily. If you need to bend your line just bend the copper tape as you stick it down. Add a second line for the negative legs. ***Make sure this tape line does NOT contact your positive line, this will result in a short circuit and a non-functional light.***
Step 4: Make the Circuit
Tape your coin cell battery to the positive copper tape line with the + side down using two strips of clear tape. Put one strip of tape on either side of the battery, leaving the center open. Use another small piece of copper tape to attach the negative line to the - side of the battery on the exposed portion. This is your switch, to turn it off simply peel back the tape.
Step 5: Tape Building Together
Now tape your building together so that it is three dimensional. Make more and turn it into a city!