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By using photopolymer extrusion in combination with two additional rotational axes , the printer developed in this work not only allows the traditional layer upon layer printing , but is also capable of free form printing .
 material: photopolymer; manufacturing process: extrusion; machine or equipment: printer; process parameter: layer; process parameter: layer
Given options, please tell me the categories of all the listed entity words.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} 
 Entities: photopolymer, extrusion, printer, layer, layer 
Answer:
 material: photopolymer; manufacturing process: extrusion; machine or equipment: printer; process parameter: layer; process parameter: layer