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With the advancement of 3D printing , variable-density cellular structures can be fabricated with high precision using this emerging manufacturing technology .
 3D printing, cellular structures, be, precision, manufacturing technology
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:
 3D printing, cellular structures, be, precision, manufacturing technology