Never got that deep into it but always wished I had the time to do more. If I was to make light boxes I would almost certainly use old white bed sheets, which I am sure would make a nice diffused light and you can't go far wrong with baking foil as a reflector. You can stick it round the turkey afterwards as well.
Another interesting material is the white opaque perspex material that you see around. A search around the internet might come up with a supplier such as this:
Perspex, Lucite and Acrylic Sheet Suppliers / Distributors - Perspex Distribution Ltd UK