Finally nailed down how I wanted this species to look. I'll make a more in depth species ref, but here's some random info for now.

They are partly made of living stained glass
They have no interior organs and are sustained by magic
Their glass parts are just like regular windows, so you can see all the way through their bodies in some places

This species is completely closed until I figure out the rest of the details

Here's the NSFW-ish version: https://www.furaffinity.net/view/23160992/