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AM processes can produce highly complex structures , constructed using both internally and externally very complex surfaces .
 manufacturing process: AM processes; concept or principle: complex structures; concept or principle: surfaces
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:
 manufacturing process: AM processes; concept or principle: complex structures; concept or principle: surfaces