People like to mimic non edible things with cake. Here is an example of a engagement ring box cake. The customer wanted everything made out of fondant, but once we told her the price she changed her mind. We did let the customer know that we never guaranteed exact color or design (they are copyrighted you know) We finished this box and were please with the outcome along with the customer.
This cake was made out of colored buttercream, airbrush color, and fondant accents. The design on the ring box is not identical to the actual box but it was close.