All the electronics are hidden in the pendant, which makes it a little thicker than I would like but it still sits nicely on my neck. The clasp is a magnet that also functions as an on/off switch. The lights are a neopixel jewel.
It’s running @Mark_Kriegsman 's Twinkle code (with the Ocean palette, of course).
This is a gift for my brother’s new girlfriend (she’s a keeper) and so I wanted to make it as user-friendly as possible. So, I’m using a Trinket Pro and Trinket Pro charging “backpack” with a small Adafruit LiPo battery, so I don’t have to remove the battery for charging… just plug in a USB cable under the turtle’s tail. Fancy!
Also, I used glow-in-the-dark polymer clay inside the shell of the turtle as a light diffuser, so when you turn it off it glows quietly to itself.