Ronny,
I’m sure your light box will work quite well in providing a flat uniform shadow-less lighting as you have described. I have used homemade light boxes myself when photographing highly reflective objects for clients.
In my fossil photography I would not use flat lighting like this however. I need to be able to show texture and surface features, all of which tend to disappear with flat lighting. A photo of a trace fossil from around here with flat lighting would end up invisible. So maybe it depends on the subject as to what lighting technique you use. I use a single flash as a main light source and a white card reflector as balance/fill. The card has to be positioned so that it softens the shadows without completely eliminating them. When photographing trace fossils I sometimes use no fill at all along with very strong side lighting (image of Phycodes flabellum trace attached)
When photographing for publications, the standard accepted lighting technique is a main light coming from the upper left of the specimen. A flat light set-up will not produce that result.
Jack