the ones that make the clear abs parts use lazers and a gel if im not mistaken the ones that use powder and liquids come out a very not clear color if the liquid is clear they come out white liquid blue they come out blud and so on... the ones that use the lazers are used by boeing and are very spendy

 

Mainly used to make scale models and model parts for molding and testing. It is really expensive... atleast from what ive seen. If you can get one, use it!