I'm looking at making some car emblems in CF.  I know I can make a mold of an existing emblem no problem.  But that means to install it on the car, I would have to remove and replace the existing emblem with the new one.

What I want to do is see if I can make the mold slightly oversized so I can make a CF replica of it slightly bigger than the original embelm.  That way it can be affixed on top of the existing emblem and will be much easier to install.

But I'm not sure how I can make that mold, any suggestions?