Selective Laser Sintering (SLS), high powered lasers + 3D printing = awesome
Selective Laser Sintering
In this method of 3D printing, a high-power laser is used to selectively fuse powdered materials one layer at a time until the object is completed. Robotic beds and a roller system allow for accurate deposition of each layer. Unlike FDM and stereolithography, the model is supported by the surrounding powdered material. This allows for complex shapes containing overhangs and intricate geometries to be printed, and is arguably one of the most versatile methods of 3D printing. When the print is completed the model must be removed from the powdered support material.
Below are two videos that describes the process in depth.
However, there is a disadvantage to selective laser sintering. While the powdered material supports the model as it is being printed, it also can become trapped in places like hollowed voids or intricate tunnels contained within the model. Despite these minor setbacks, some of the most impressive 3D objects have been created using this method.
The materials for selective laser sintering are diverse. The most common is plastic nylon. Nylon is also sometimes mixed with aluminum powder to produce the material alumide. Ceramics and metals such as steel and titanium can also be used in SLS. Printers of this type are too expensive for the hobbyist, costing hundreds of thousands of dollars. However, affordable 3D printing services like Shapeways allows anyone to access this technology.