This is the same technology used in those ovens that have the glass panel over the controls, but they use ICs. The principal is the same however, they both detect (I think) the small electrical signals that people give off and amplifies this to a useful level. If this is wrong correct me, but all I know is that this works.
(This design works great for LEDs. I am making a touch LED flashlight that runs off rechargeable batteries, but I am not sure what batteries to get yet.)
Step 1: Parts
-4 x 2N3906 PNP transistors or similar (note below about transistors)
-1 x 1N914 diodes
-1 x 10v 1000uF capacitor (keep the voltage below 10v / Caps rated voltage or it will
-1 x Barrel jack
-1 x 9v 300ma adapter
-1 x 120 Ohm resistor (Brown, red, brown)
-1 x Ceramic capacitor
-some shield wire (I don't use it because I don't have any but if you do use it!)
-some copper clad is nice to have but not needed
-ugly perf board
-Breadboard/protoboard are handy as well
-tin snips for copper clad and ugly perf board
*Note: The transistors I used are random transistors similar to 2N3906 but I live in Canada and can only get a package of transistors "similar" to 2N3906 so protoboards are good to test this out on. Mine are bi polar and let some electricity through one way all the time wether they are off or turned around let no electricity through when off. Test the different combinations to get the way that works best. 2N3906 should work fine in this circuit though I have not tried it.