Pre-production samples that look and function like the final manufactured product.

Very often the prototype stage can be accomplished with the aid of Rapid Prototyping (and 3D Printing) models that are inexpensive, laser accurate physical models that are made directly from the 3D computer files.

Physical models that simulate how a product will look and feel while not necessarily being fully functional.

I have an in-house model making facility and considerable outside resources to produce very sophisticated prototypes.