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Nowadays , a new type of technology is emerging , additive manufacturing , also referred to as 3D printing , that allow building up pieces by adding materials layer-by-layer , based on a computerized 3D model .
 concept or principle: technology; manufacturing process: additive manufacturing; material: as; manufacturing process: 3D printing; concept or principle: materials layer-by-layer; application: 3D model
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: manufacturing standard, machanical property, manufacturing process, material, engineering feature, process parameter, machine or equipment, application, process characterization, enabling technology, biomedical, concept or principle 
Text: {0} 
Answer:
 concept or principle: technology; manufacturing process: additive manufacturing; material: as; manufacturing process: 3D printing; concept or principle: materials layer-by-layer; application: 3D model