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.