I really wanted a light box but buying a commercially made item at nearly $100 seemed ridiculous, so I also made one. I got the idea from a website and it is fairly simple. It is just an 18" cube made of 1/2" plastic water pipe, elbows and T's. I drape a couple yards of thin white cloth over it all, place different coloured sheets of bristol board inside (if necessary), aim several bright desk lamps at it and take pictures of things inside.
Although more costly than a cardboard box it has the advantage of being partly disassembled and folded flat for storage. Like Mike Cash suggested it can be placed over the top of large or taller items. I haven't used it in a while; I think you have inspired me to drag it out this weekend have some fun.