I use my printer about 10 hours a week to print prototype parts for product development as well as for printing personal items. 3d printing is not a revenue stream for me at this time. But it is an invaluable tool in my design toolkit. I can print items in a few hours that would have taken days to create in the traditional "model making" manner. Plus, the parts are actually able to be put to use. Most design models are crafted from other materials that simulate what they'd actually be made from. They are frequently to be used for aesthetic evaluation purposes only and can't be used. With 3d printed parts, the aesthetics can be assessed and then they can be used in many cases to test them.