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However , conventional CAD-based design techniques are inefficient and usually fail to obtain the optimal scaffold design because a prohibitively large number of trials would be required in order to achieve a balanced performance , e.g. , desirable stiffness and good permeability .
 enabling technology: CAD-based design; engineering feature: scaffold; engineering feature: design; material: be; concept or principle: performance; machanical property: stiffness; machanical property: permeability
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:
 enabling technology: CAD-based design; engineering feature: scaffold; engineering feature: design; material: be; concept or principle: performance; machanical property: stiffness; machanical property: permeability