You've already got the wrong materials for a light table, You don't use glass, you use acrylic. The problem with glass is that it doesn't diffuse light, it reflects and refracts it. If you're thinking of using a textured glass, you're still in the wrong ballpark, because even though it will diffuse it
a little it will give uneven results and the texture will give off inaccurate results similar to putting film negatives or transparencies on an LCD monitor--you don't see the detail on the film, you see the pixels. Using the back light of an LCD probably wouldn't be bright enough anyway, and since you're using glass, it won't be diffused and will give off uneven light, which is horrible for not only film, but drawing too.
You need Acrylic and flourecent light fixtures to put in the box. Anything else and it could give off way too much heat and it could cast colors that with mixed lighting, the eye may have a hard time balancing.