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This study presents the surface characteristics of aB-built specimens manufactured by selective laser melting ( SLM ) , where improvement of the surface can be achieved by post-processing operations .
 surface, manufactured, selective laser melting, SLM, surface, be, post-processing
Please list all entity words in the text that fit the category. Output format is "word1, 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:
 surface, manufactured, selective laser melting, SLM, surface, be, post-processing