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The Cornell University and the University of Bath have designed the first open-source 3D printers which are widely recognised in the area : Fab @ home and RepRap .
 engineering feature: designed; concept or principle: open-source; machine or equipment: 3D printers; process parameter: area; application: RepRap
Please list all entity words in the text that fit the category.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} 
Answer:
 engineering feature: designed; concept or principle: open-source; machine or equipment: 3D printers; process parameter: area; application: RepRap