This LED heart is made of 16 leds, some 100 ohm resistors, a 2N222 transistor and 4 AA batteries.
I’ll post a tutorial soon, but if you want to try to understand my project you can download and print the board I designed:
Transfer it to the board
Erode at iron perchlorate (this is not the original drawing I posted above, but the eroding process will make it look like this)
Drill it and insert components
Paint the front side
You can even try different LED colors!
Solder all the components like this
Now you can hot glue a 4xAA batteries holders on the backside to power the leds.
Solder the battery pack!
You got the power!
(In the middle of the board you should place a PIC header and program your own PIC to blink the leds. Or you can use a jumper to automatically activate the leds when you switches the board on. I had to do it because I had problems with my PIC burner)