I originally saw the posting over at EvilMadScientist.com about creating Edge-lit LED Holiday Cards here: www.evilmadscientist.com/article.php/edgelit2and wanted to try to simplify and or improve the design. Much credit goes out to those guys for their original idea. By employing an over-sized paper punch and some hot melt glue I came up with some very nice cards to send in time for Christmas that fade and change color.

Step 1: Things I Used

Materials:
1. 8.5"x11" Card Stock
2. 4 3/8" x 5 3/4" Invitation Envelopes
3. Clear Plastic Poster Board (between 1/32" and 1/16" Thick) ($1.00 at craft stores)
4. Dark Poster Board Blue or Black ($1.00 at craft stores)
5. 3mm Color Slow Fading or Rainbow LED Wide Viewing Angle (16¢ to 30¢ each on Ebay )
6. CR2016 Lithium Coin Cell Battery (Less Than $1.00 each on Ebay)
7. Scotch Tape
8. Electrical Tape

Tools:
1. Scissors
2. Needle-nose Pliers
3. Exacto or Small Utility Knife
4. Clever Lever Extra-Giga Scalopped Square Paper Punch ($12.00 at craft stores)
5. Hot Melt Glue Gun
6. Push Pin
7. Standard 1/4" Handheld Hole Punch

Step 2: Prepare Card Stock

I wanted to have a family picture on the inside (back flap) with a greeting message. I created an image with my graphics program and sized it to print twice on the right most side of the card stock sheets. This way I could cut the sheets in half, fold them at 4 1/4" and have two cards.
After printing, cutting and folding several sheets, I used the large paper punch to knock out 2 1/2" square window holes on the front of each card. Make sure you save the square punches of card stock to use later on in step 4.

Step 3: Prepare the Clear Poster Board

I first did a search on Google Images for a suitable snowflake outline image to create templates. I re-sized the image to fit within a 2" square and printed several on each page of plain white paper with about a 1 inch border around each snowflake. I then cut the clear poster board into 3" squares and taped a single snowflake template in the center of each one. Be sure to leave the protective paper on the plastic to keep it from scratching or scuffing. Then placing the plastic squares on a few layers of cardboard it was time to start poking holes with the push pin to transfer the pattern to the plastic. If you are making several cards you may want to make a better, more comfortable push pin (my fingers got sore) by inserting a medium sized sewing needle backwards into the end of a wooden dowel. After the pattern is completed, I removed the paper template and the protective paper and cut a small groove at the bottom to accept the crown of the LED.

Step 4: Prepare the On/Off Switch

I devised a simple On/Off switch to help conserve the battery life and to make it simple for someone to use. Using a paper punch square left over from step 2, I cut a small 3/4" long horizontal slit about 1 inch from the bottom center. I then created a pattern of smaller H shaped pull cards (see pictures) that were 3/4" wide at the center section and fold over tabs at each end. At the top center of each pull tab I made a hole using a 1/4" hole punch. By folding the tabs over at one end you can slide it into the slit in the paper punch square. Folding the tabs back flat will lock it into the slit so that it only moves up and down. When the tab is pulled down the bent LED lead drops into the hole and makes contact with the battery turningit on. When pushed back up into the slit, the tab slides between the bent lead and the battery to shut it off.

Step 5: Prepare and Mount the LED

Using needle-nose pliers, bend 1/8" of the end of the LED's shorter (negative/cathode) leadat a 45° angle away from the longer lead. Next bend the same lead at a 45° angle back towards the longer leadat 1/4" from the end making a "V" shape at the end pointing towards and touching or going slightly past the longer lead.While holding the LED leads perpendicular to the snowflake plastic square surface and inserting it into the crown hole created in step 3, put a small amount of hot melt glue on the LED to hold it in place until it cools. Cut a small 1/2" long piece of electrical tape and place it over the LED on the long lead side, this will prevent the LED from shining through the card stock front.

Step 6: Final Assembly

1. With a card created in step 2 open showing the inside and laying flat, use small drops of hot melt glue on each corner of the snowflake/LED sheet from step 4. With the bent LED lead facing up and the longer lead laying on the card stock, place and mount it over the window in the card with the LED just below the window's bottom edge.

2. Cut a 4" x 3 1/2" square of the dark poster board and mount it over the snowflake/LED sheet with hot melt glue to within 3/4" on either side of the LED leaving the area near the LED clear. Do not get hot melt glue on the LED leads!

3. Slide the CR2016 battery (positive side down) between the LED leads until the bent lead is about 1/4" from the bottom edge. At this point the LED should be lit and working, if not, make sure the bent (shorter lead) is facing up and is pressing against the battery. If not, remove the battery and try bending the leads slightly so they touch each other and re-inserting the battery. Tape the battery with scotch tape on the left and right leaving an open 1/4" strip where the bent LED lead contacts the battery.

4. Slide the top of a pull tab from a prepared On/Off switch (step 4) between the bent LED lead and the top of the battery until the hole in the tab allows them to re-connect. Use a small amount of hot melt glue to secure the outside rim of the switch's paper punch square over the LED and battery. When the glue cools, the pull tab should now slide up and down to turn the LED on and off.

Step 7: Sit Back and Enjoy!!!

It seems like a lot of steps but really it is not all that hard and I was able to crank out 20 cards in about three hours. The whole family got involved and we had an assembly line going.The cards worked great and we had a blast making them.