Which of the following is NOT a rapid prototyping process?

Traditional machining is not considered a rapid prototyping process because it involves subtractive manufacturing techniques, where material is removed from a solid block to create a part. This process can be time-consuming and often requires multiple setups and tool changes, which is not conducive to the rapid iteration and quick prototyping that is characteristic of rapid prototyping methods.

In contrast, rapid prototyping techniques such as Fused Deposition Modeling, Selective Laser Sintering, and Laminated Object Manufacturing all focus on additive manufacturing, where material is added layer by layer to build up the desired shape. These processes enable quicker creation of prototypes, allowing for faster design iterations and testing. Therefore, traditional machining stands apart from these quicker, more efficient additive techniques, solidifying its position as the correct answer to the question.