The blink pattern is an actual firefly song of a type of Japanese firefly. It is a scaled down version of the Jar of Fireflies code that my partner wrote. I have included the code here.
Step 1: What you need
copper tape (from a glass supply store)
a glass cutter (from a glass supply store)
pliers (glass pliers are best but you can substitute regular pliers and coat the tips with rubber like the ones below)
tiny wires, preferably two different colors
ATTiny45 chip (code attached*) (Digikey #ATTiny45v-10SU-ND)
LED (Digikey #160-1423-1-ND)
CR2016-1F2 battery (Digikey #P222-ND) (Really, any 3v battery will do. This one was chosen for form factor.
*Getting the code on the chip could be its own Instructable. When I am a microcontroller guru someday I will post on how to do that.
Step 2: Score & Cut the glass
Art glass is a bit softer than window glass. It is much easier to cut as well. Draw your lines on the glass. Dab a little mineral oil on the cutting wheel to keep it moving nice and smoothly. Apply slight and even pressure and roll all the way to the other side of the glass (past your markings).
Glass pliers are very nice and specifically designed to break your glass along your score. They're kind of rounded on the ends and have rubber pads to protect the glass from scratching. The pliers below are regular pliers that have been dipped in liquid rubber several times to get the same effect - mostly anyway. Either way, they will break the glass *way* better than your hand.
Score and break until you have a square.
Step 3: Prepare picture
Cut a hole in your picture and your aluminum that the LED can shine through.
There will be four layers for your picture before we start on the electronics. Stack layers in the following order:
As you can see, we're using the vellum to diffuse the LED light.
Copper tape is not difficult to work with. Line the edges first. Squish two opposite sides down flat. Run your fingernail or other flat surface over them to make the edges sharp. Then squish the other two sides taking care to make nice corners. The flatter your fold against the glass the nicer your solder will look when you're finished.
Step 4: Solder the edges
Use your 80 gigawatt soldering iron to solder around the edges. If you've never used a stained glass soldering iron before get ready for a treat. They're loads of fun. They heat to around 800 degrees F so don't get them anywhere near electronics or you'll fry everything. That's why we're doing this beforehand.
Bend a thin wire around a paintbrush to form a jump ring. This will give you somewhere to hang your pendant.
Step 5: Solder electronics
The LED is probably the most difficult to solder. It is quite handy to stick it to some double sided tape before you begin. You want to have more than one handy just in case. They're invisible if you drop them!
I have marked Pin 1 on the back of my chip with a white dot. You can also tell by the printing on the back and dot on the front. You may need to cut the soldering leads on the battery and the switch to fit. I recommend you wait until everything is soldered before trimming though. Solder everything per the schematic and glue down the chip & switch.