How to Make a Simple Electric Generator
To make a simple electric generator, start by building a small frame out of cardboard. Next, wind the copper wire tightly around the cardboard several times, leaving 16-18 inches of wire loose on each end. Strip 1 inch of insulation off the ends of the wire and connect the wires to an electronic device. Then, glue the magnets to the shaft, turn the shaft until you see the ends of the magnets hit the frame, and spin the shaft as fast as possible to power the generator!
Cut the cardboard. Cardboard will serve as the frame and support for your simple generator. Use a ruler to measure a cardboard strip that is 8 centimetres (3.1 in) by 30.4 centimetres (12.0 in). Cut this strip out with scissors or a utility knife. This single piece will be folded to form the frame. Mark the cardboard. Use a ruler to measure along the length of the cardboard. Make your first mark at 8 centimetres (3.1 in). Your second mark should be at 11.5 centimetres (4.5 in), and your third mark should be at 19.5 centimetres (7.7 in). The final mark will be at 22.7 centimetres (8.9 in). This creates segments of 8 centimetres (3.1 in), 3.5 centimetres (1.4 in), 8 centimetres (3.1 in), 3.2 centimetres (1.3 in), and 7.7 centimetres (3.0 in). Do not cut these segments. Fold the cardboard. Fold the cardboard along each mark. This will make your flat piece of cardboard into a rectangular frame. This frame will house the components of your electric motor. Slide the metal shaft through the support frame. Push a nail through the center of the cardboard frame. Make sure you go through all three pieces of cardboard that are folded into the center. This will create the hole for your shaft. You can now insert a metal shaft, or use the nail as your shaft. The metal shaft does not have to be anything in particular. Any piece of metal that will fit through the hole and come all the way out the other side of the frame is acceptable. The nail you use to make the hole will work perfectly. Wind the copper wire. Make several turns around the cardboard box with enamel coated copper wire (#30 magnet wire). Wind 200 feet (61 m) of wire as tight as you can. Leave about 16 to 18 inches (40.6 to 45.7 cm) of wire loose on each end to connect to your meter, light bulb, or other electronic device. The more "turns" or winds you make around the cardboard frame, the more power your generator should produce. Strip the ends of the wire. Use a knife or a wire stripper to remove the insulation from each end of the wire. Remove about 2.54 centimetres (1.00 in) of insulation from each side. This will allow you to connect the wire to an electronic device. Connect the wires to an electronic device. Attach the two wires you have loose at the ends of the windings to a red LED, #49 miniature bulb, or a 1.5V grain-of-wheat lamp. Or, connect the test leads from an AC voltmeter or multimeter to them. Keep in mind that you are producing a very low voltage, and larger devices (e.g. a regular light bulb) will not be powered by this generator. Glue the magnets to the shaft. Use a high strength hot melt glue or epoxy to glue four ceramic magnets to the shaft. You want the magnet to be stationary with respect to the shaft. The magnets should be glued onto the shaft after the shaft has been inserted into the frame. Allow the glue to dry for several minutes (the instructions on the container can tell you exact drying times for your type of glue). For best results, use 1x2x5 cm ceramic magnets (these can be found online for a reasonable price). Glue them so that two magnets are facing the coil with their north side, and two are facing the coil with their south side. Turn the shaft with your fingers. This allows you to see if the ends of the magnets hit the inside of the frame. The magnets must turn freely, but as close as possible to the walls of the frame. Again, having the magnet's ends as close the copper wire windings as possible will increase the "exciting" action of the magnetic fields the magnet produces. Spin the shaft as fast as possible. You may want to wind a string around the end of the shaft, then pull it sharply to turn the magnets. You could even just spin it with your fingers. As the shaft turns, you should get a small voltage (enough to light a 1.5 volt light bulb). You could improve the power output by putting a pinwheel on the end of the shaft and connecting it to an electric fan to turn the wheel. Keep in mind that this is only good to demonstrate the operation of the generator since you use more electricity turning it than you create. 
Cut the cardboard. Mark the cardboard. Fold the cardboard. Slide the metal shaft through the support frame. Wind the copper wire. Strip the ends of the wire. Connect the wires to an electronic device. Glue the magnets to the shaft. Turn the shaft with your fingers. Spin the shaft as fast as possible. 