Here are instructions for making your own lightbox using a cardboard
box and translucent fabric/whatever.
Hardly seems worth the trouble, when you can buy an already made one
for just $44.00 at
and it has clips to hold the background.
But, I post the cardboard one here for students on a budget and
other die hard do it yourselfers.
Metalsmith, Certified PMC Instructor
Hard to Find Tools for Metal Clay