Any type glass would work especially if it were mixed, ie not everything one kind. I'd be fine having it in the walls. But if overhead I'd want chicken wire or something tacked on below the glass so it doesn't fall on my head.

You can see my used window glass gh photos on the gh opinion thread.

What I'm using are some old storm windows that were being removed from a house we were renting when they were putting in replacement windows. I am making a 4' by 8' structure that will fit exactly over one of my raised beds, and I am installing the storm windows so they open, from the top or the bottom, from the outside. This looks like it will work well.