2035
The main methods to generate irregular porous structures with complex internal surface topologies are either filling or hollowing materials from an initial design via specific algorithms .
 machanical property: porous; engineering feature: surface topologies; concept or principle: materials; engineering feature: design; concept or principle: algorithms
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:
 machanical property: porous; engineering feature: surface topologies; concept or principle: materials; engineering feature: design; concept or principle: algorithms