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One of challenges for weld-based Additive M anufacturing is to build overhanging structure or tilt structure at a large slant angle , because liquid metal on the boundary would flow down by gravity due to lack of sufficient support .
 material: Additive; process parameter: build; concept or principle: structure; engineering feature: tilt structure; process parameter: slant angle; material: liquid metal; engineering feature: boundary; application: support
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:
 material: Additive; process parameter: build; concept or principle: structure; engineering feature: tilt structure; process parameter: slant angle; material: liquid metal; engineering feature: boundary; application: support