After coming to the conclusion that 1) I needed a lightbox and 2) it needed to be durable enough to survive being shuffled around and dismantled a lot. I do all my work inside a small apartment so a lightbox large enough to hold the items I usually make would be too large to easily stow. I wound up using 1/4" hardboard for the structure and lining it with poster board. The tracing paper was left over from a starter leathercraft kit I picked up from Tandy five years ago (always figured I'd use it someday). The light was provided by a couple work lamps with 100W Daylight LED bulbs. I'd originally tried CFL bulbs to keep the costs down, but everything was coming out all yellow. The LED's were pricier but I think they've turned out pretty well. If anyone's particularly interested, I wrote all the details and posted all the pictures on my little, personal "blog-thing" here
A completed box:
After I figured out it would work better on its side:
Broken down:
With CFL bulbs:
With LED bulbs: