I don't know exactly what you mean by molding clay, since most of the clays I've been using for making molds are wax based and are NOT appropriate for directly wearing. Maybe you mean apoxie sculpt or other hard air drying clays?
I've used it to make vac bucks stuff and it's really strong and easy to use. Just wet your hands or smoothing tool and it gets pretty smooth. Then to get even smoother you can use a fine sanding sponge to knock down any inconsistencies.
I have the entire build here.