Hello Instructables! This is my entry for Make It Glow Contest.
Who said that electronics can’t be romantic? We can use it to show a person our love, and it is exactly what we are going to do: a present, as simple to realize as wonderful to see, to give to the person we love.
It could be a great gift for Valentine’s Day or anniversary.

The idea is to realize a casket which has inside some little red LEDs arranged in a heart shape.
A switch turn the LED on and off.

You can see the final result in the picture above. It's amazing!

Step 1: What We Need

These are the components we need:

a casket (mine is priced ~€2.50);
27 red LED (~€6.00);
one 220Ω resistor;
one switch;
one battery case (4 AA batteries);
black cardboard (better if rigid);
soldering station
optional: a third hand (~€6.00) is really useful during soldering.

Step 2: Making the Heart

Cut a piece of cardboard of the same height of the casket, but with a greater length: on one side, a flap will be sticked inside the casket, while, on the other, the cardboard encloses the battery case. My casket’s size is 12 x 6.5 cm, so the cardboard is ~16 x 6.5 cm.

Now, the heart. Using a 2D vector graphics software (I recommend Inkscape), draw a heart, formed by 27 circles, diameter ~0.6 cm. I provided the one I made, but feel free to modify it as you want.
Print it, place it on the cardboard, and make holes in correspondence to the circles: there you will place LEDs.
I used a belt puncher.

Step 3: Soldering

The third phase begins: soldering.
Insert LEDs in the cardboard through the holes and connect them in parallel, which means every positive leg with positives and every negative with negatives.
I recommend to use a third hand and insulating tape.

Pay attention: do not connect a positive leg with a negative one, or the circuit won't work!

Connect one positive leg to the 220Ω resistance, and then to the switch (make another hole in the cardboard for it).
Finally, close the circuit connecting the battery case.

Step 4: Conclusion

Enclose the battery pack within the cardboard. On the opposite side, fold a little flap and stick it inside the casket.
You are ready to show your love: turn it on!
I assure it's as beautiful to look at, as simple to make.

(Sorry for image's bad quality)

If you like this instructable, please vote me.
Thank you!