This is just a cardboard box with the sides cut out and replaced with wrapping tissue. The tissue-covered "windows" allow for the light coming from the two lamps flanking the box to be diffused into the box. The baby shoes are sitting on a white poster board, or the "stage". See the before and after pictures of the gum paste baby shoes below.
Without the Light Box
With the Light Box
After a bit of photo editing
Ahh, I impress myself sometimes :-D