Here's what's happening with the 3D printed tentacles!
The tentacles have a hole in the bottom that fits an led. After trying a bunch of colors I think they look best with a green led. Here's a parallel circuit on my breadboard with 5 green leds and a tentacle on top with the light shining through. I'm planning to make this into a headband, hopefully in time for Aquarium Night at DragonCon.