Quote Originally Posted by Shesh
There were 3 problems I encountered when I considered the x-ray viewers available via glass shops -
1. Could not find one 48" long.
2. The ones that used glass imparted a distinct dull muddy color and did not diffuse the light enough.
3. The ones which used acrylic used a very thin layer of acrylic (and hence could not support my bending over the box and viewing the film with the loupe.

I guess, if these problems can be avoided, x-ray viewers would be the way to go.
I don't bend over my X-Ray lightbox. But if you want to, a sheet of glass on top of the acrylic should solve the problem. Mine is about 48" long. So they do exist. I guess even longer ones exist.