Changing the height may have made a difference it really is kind of hard to tell. I plan on carving with some 1/4 white corian in a couple of days when I can get back out to the shop.
Here are a couple of pictures of the pine cone that I carved in clear material. When I put it in the light box I put some 1/8 thick white plastic behind it that I bought at the local Menards. At the time I didn't have any white corian to carve with. I thought that with just the clear, and maybe a dark background it would look good.