How are the size and the complexity of the models?
Do you want it solid or hollow? (It depends the size, hollow means cheaper, but weaker).
Personally I made some jewelry, among other different things, but probably this work is the most closest to the work you're requiring.
I use Maya and Zbrush, so I'll use .stl format.
Well, with that is enough to start. Just say me something if you see OK the purpose.