4971
A test case using a fused filament fabrication ( FFF ) 3D printer was implemented , demonstrating in situ error detection of localized and global defects .
 fused filament fabrication, FFF, 3D printer, in situ, error, defects
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:
 fused filament fabrication, FFF, 3D printer, in situ, error, defects