I designed this to direct light onto my working space, it's a shelf, so it's got a ceiling that's about 50cm high. It's glued with epoxy and is starting to show signs of warping, but I doubt that it's going to get unstuck. I'm using a fluorescent bulb so that explains the warping issues, as it gets to about 50°C.

If I were to solve the problem of not having a light again, I'd use led strips. They are basically as thin as a few pieces of paper and a lot more efficient and nicer looking.