580
In their research , restrictions and recommendations were presented based on experimental measurements of different characteristics such as cavities , walls , bores , gap , hollow cylinder , overhangs and support structures .
 concept or principle: research; concept or principle: experimental; material: as; process parameter: overhangs; engineering feature: support structures
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:
 concept or principle: research; concept or principle: experimental; material: as; process parameter: overhangs; engineering feature: support structures