Wild guess: a laser pen for transmitting audio?
You are right on track, but it sends a signal which is collected on another diode and processed by my pc sound card in order to complete it's mission.
Now a laser is another one of my projects actually a cnc laser cutter to be precise but we'll get into that some other time
At first glance it appears to be a flashlight, but I suspect it is more complicated than that.
It is a "flashlight
(penlight actually seeing as that clear tube is actually a disassembled kaleidoscope pen I had in a box-o-crap from years ago.)" of sorts with a specific purpose having nothing to do with illumination, and you are correct this is only one third of it, though if I posted the other factors it would give it away.
*votes for taser, even if it doesn't look remotely possible with that setup...not that I know anything about them*
HA! have built one of those, safer and for the leisurely hackster cheaper to buy one
