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This article proposes a new method for reducing the amount of support material required for 3-D printing of complex designs generated by topology optimization .
 support material, 3-D, designs, topology optimization
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:
 support material, 3-D, designs, topology optimization