2029
Its goal is to generate either lightweight structures with unexpected mechanical properties , similar to the lightweight design methods mentioned in the last section , or multi-functional surface structures as addressed here .
 machine or equipment: lightweight structures; concept or principle: mechanical properties; concept or principle: lightweight; engineering feature: design; engineering feature: surface structures; material: as
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:
 machine or equipment: lightweight structures; concept or principle: mechanical properties; concept or principle: lightweight; engineering feature: design; engineering feature: surface structures; material: as