What manufacturing process involves successively layering material to build a part?

Additive manufacturing is the correct answer because it specifically refers to the process of creating objects by adding material layer by layer. This approach contrasts with traditional methods where material is removed (subtractive manufacturing) to create a part. In additive manufacturing, materials such as plastics, metals, or composites are deposited in layers according to precise specifications, allowing for complex geometries that are often impossible or costly to achieve with subtractive techniques.

Slicing technology, while relevant in the context of additive manufacturing, describes a specific step in the process where a digital model is divided into layers for 3D printing, but it does not by itself define a manufacturing process. Traditional machining involves cutting, drilling, or shaping materials, which is fundamentally different from building objects through accumulation of layers. Thus, additive manufacturing is the best fit for the process described in the question.