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Reflecting the strategy of some companies like ExOne or Voxeljet , the professional 3D printers can be combined to the production line and offer the largest printers on the world market for 3D printing of sand and metal materials .
 application: companies; machine or equipment: 3D printers; material: be; manufacturing process: production line; machine or equipment: printers; manufacturing process: 3D printing; material: sand; material: metal materials
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:
 application: companies; machine or equipment: 3D printers; material: be; manufacturing process: production line; machine or equipment: printers; manufacturing process: 3D printing; material: sand; material: metal materials