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The most common method for Additive Manufacturing ( AM ) of polymers is melt extrusion , which normally requires several pre-processing steps to compound and extrude filament feedstock , resulting in an overall long melt residency time .
 Additive Manufacturing, AM, polymers, melt extrusion, extrude, feedstock, melt
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:
 Additive Manufacturing, AM, polymers, melt extrusion, extrude, feedstock, melt