An object manufactured by a CNC machine is an example of which kind of rapid prototyping process?

• A. Additive
• B. Subtractive
• C. Formative
• D. Destructive

Answer: (B)

When thinking about rapid prototyping methods, the key idea is whether material is added to build the part or removed to shape it. A CNC machine works by starting with a solid block of material and surgically removing material with cutting tools to reveal the final geometry. That removal-based approach is called subtractive manufacturing. In contrast, additive processes build up the part layer by layer (like 3D printing), formative processes shape material without removing it (such as molding or casting), and destructive processes refer to methods that damage or break down material. So, the object produced by a CNC machine fits best as subtractive rapid prototyping.