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Although 2D patterned surfaces provide outstanding insight into optimal patterned architectures by facilitating the analysis of various myoblast responses , it can be difficult to achieve complex 3D structures with microscale topographical cues .
 2D, surfaces, be, 3D structures, microscale
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:
 2D, surfaces, be, 3D structures, microscale