The article is mixing stereolythografy and laser sintering. When the patents of laser sintering will expire the laser scanner still has to be very accurate. An

The article is mixing stereolythografy and laser sintering. When the patents of laser sintering will expire the laser scanner still has to be very accurate. And accurate laser scanners are expensive even without patent. It might be different for stereolythografy. With a good beamer high resolutions are possible. But then there are materials. The resin used for stereolythografy is expensive because of patents. The powder used for laser sintering is expensive because of patents.