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This paper describes a facile method to fabricate complex three-dimensional ( 3D ) antennas by vacuum filling gallium-based liquid metals into 3D printed cavities at room temperature .
 fabricate, three-dimensional, 3D, liquid metals, 3D printed, temperature
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:
 fabricate, three-dimensional, 3D, liquid metals, 3D printed, temperature