(1) Luxeon I blue 1W LED (SparkFun Electronics; $4.95)
(1) Luxeon aluminum breakout SparkFun Electronics; $2.95)
(1) CR2032 with legs (BG Micro; $0.65)
(1) SPST switch (RadioShack; $2.99)
(2) Short length of wire
(12+) Greeting cards
Step 1. Cut all of the greeting cards in half along the fold line. Both landscape and portrait cards will work. Discard unwanted halves. Set aside four card halves for the top row of the tower. Use a decorative punch to make random holes in a couple of the cards. These holes will allow light to stream from the final tower lamp and cast interesting shadows on your surroundings.
Step 2. Create a template for cutting 8 slits in each greeting card half. Don't cut the four set aside card halves, yet. There should be two equidistant one-half-inch cuts on each side of every card--for a total of eight slits per card.
Step 3. Cut the four set aside card halves with only 6 slits per card. Don't cut slits in one of each card's long horizontal sides. This side will be the top of the tower.
Step 4. Fold all cards in half--like a book.
Step 5. Slot two cards together along each width. This action will form two corners and one complete side of the tower base.
Step 6. Slot another card into either free end of the two cards joined in Step 5. You now have three corners and two complete sides of the tower base.
Step 7. Finish the tower base and the last two sides by slotting another card into both of the two remaining free ends. Row 1, the tower's base, is now finished. Continue adding rows by following steps 5 through 7. Join rows together by slotting the completed row's upper side slits into the new row's bottom slits.
Step 8. Assemble the Luxeon LED and Luxeon aluminum breakout according to instructions in the Luxeon datasheet.
Step 9. Connect the negative (-) leg of the battery to one of the negative (-) pads on the Luxeon aluminum breakout. Solder one end of a short length of wire to a positive (+) pad on the Luxeon aluminum breakout and the other end to one of the switch's terminals. Solder one end of another short length of wire to the positive (+) terminal of the battery and the other end to the remaining switch terminal. Attach the switch through the side of the card tower.
It is pretty cool when backlit, but kind of a messy collage otherwise. Personally, I would just pick out my favorite card designs (I use www.kerstencards.com for a lot of mine but you could even make your own) for any specific occasion and mount them in a thick frame so they could always be backlit. Interesting idea to save the guilt of throwing away greeting cards though!