What you need to make one is this:
-3300 uF capacitor
-1000 uF capacitor
-2n3904 or 2n2222 transistor
-2 x 100K resistor
-LED (not necessary but it uses otherwise wasted energy so why not.....)
-coil. You can buy these at Solarbotics , http://www.solarbotics.com .Or salvage one from a videorecorder.
-magnet (neodymium magnets are great for this)
This is for the electronic circuit,what you use for the stand is up to.Make it big,make it small,make it short or make it tall(yes,I'm a poet ;) )At this time I wasn't sure what I was going to use for a stand yet but I did know I wanted to use a wooden ball as the pendulum bob(the part on the end of a pendulum).
Step 1: The electronics
Take the 2n3904 and 2n3906 transistor (hold the flat side towards you).Solder the right lead of the 3904 to the middle lead of the 3906.
Get the two 100 K resistors and solder them together.Solder the right lead of the 3906 transistor to one end of the resistors.
Solder the middle lead of the 3904 transistor to the the middle of the two resistors.
Now lets join the two parts of the circuit together.The left lead of the 3906 transistor goes the positive side of the diode.The left lead of the 3904 transistor goes to the negative lead of one of the capacitors.
At this time I usually put the electronic circuit to the side and start working on the base(it is easier to solder the LED,coil and solar cell on later when you decide where to place them on the stand)
Many thanks to Solarbotics(http://www.solarbotics.com )for letting me use the image of the circuit.