I have seen fondant decorated cakes with the designs actually rolled?? in to the fondant instead of laying them on top. I tried this with circles and stripes but when you roll it the circles and stripes spread. Does anyone know how to do this "flush", smooth design?

I would also appreciate advise on the same technique as above but using a marbling affect.

Thanks!

I think you might be describing an inlay like this http://www.wilton.com/technique/Fondant-Inlay

Thank you. It is easier than I thought!