2042
Apart from the internal surface structure generation , external surface structure design also attracts attention since using AM to print complex shapes for art or customized shapes has become popular .
 engineering feature: surface structure; engineering feature: surface structure; engineering feature: design; manufacturing process: AM; manufacturing process: print; machanical property: complex shapes; application: art
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:
 engineering feature: surface structure; engineering feature: surface structure; engineering feature: design; manufacturing process: AM; manufacturing process: print; machanical property: complex shapes; application: art