I made this before I made the instructable, so it might not be clear.
If you want me to start selling them on ebay, let me know.
Step 1: Get your legos
-a 2x6 lego brick
-a 2x6 matching lego panel
-small flexible insulated wire
-1 superbright LED (white is nice, but you can get a color to match a brick)
-a switch (i used a small toggle switch from RadioShak)
-3 LR1130 button cell batteries.
-needle nose pliers
-something to make the holes in the plastic for the LED and toggle switch
Step 2: Prep the brick
then, using any method, make two holes in the ends of the brick. the hole for the LED should be small, and steadily make it bigger, until the LED fits snugly in the hole.
make a hole for the switch, just larger than the threads. put the switch in, and screw on one nut(or two). dont make it too tight.