4852
While additive manufacturing ( AM ) , commonly known as 3D printing , has been in existence commercially for ∼30 years , desktop 3D printers are a relatively new and rapidly growing market segment .
 additive manufacturing, AM, as, 3D printing, desktop 3D printers
Please list all entity words in the text that fit the category. Output format is "word1, 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:
 additive manufacturing, AM, as, 3D printing, desktop 3D printers