To answer your original question…Black background (fabric, t-shirt, etc), natural light source (the sun), camera far away from the object to not cast a shadow or cause any odd imaging.
As an extra side note, I was working on a project a few months ago to truly capture the holo pattern of a card in an image like this…
The rest of the thread with me experimenting is here:
www.elitefourum.com/t/digital-archiving-true-holo-of-collection-worth-it/30647/1
Life has been a bit more busy at the moment so I haven’t had a lot of time to really try to tackle perfecting and fully automating the process, but I plan to get back to it as some point.
It can be done!