Plastic parts not only benefit from designs that are pleasing to the eye, they also benefit from touch. Smooth as glass, or rough to indicate strength and durability. A prototype is a tool to help you see not only your concept in reality, but to objectively decide how it will fare in the marketplace. Texture plays a huge part in product perception.
Learn more about the role psychology plays in design and plastic prototypes.
Texture on a prototype can be a functional component of its design. Imperfect parts can be camouflaged by the right texture. Is the prototype designed for frequent handling? Texture can be used to hide finger prints and improve the grip for the end user. Texture can also be used to reduce part wear from friction. But most often, texture is used for aesthetic reasons.
The proper term for the science of friction is Tribology. Rubbing two sticks together to build a fire is an example of friction. We can take the principle and apply it to the injection molding process in order to improve cycle times by reducing friction upon the moving parts. Less friction equaling a faster process.