Selective laser sintering (SLS) machines are made up of three components: a heat source to fuse the material, a method to control this heat source and a mechanism to add new layers of material over the previous. The SLS process benefits from requiring no additional support structure, as the powder material provides adequate model support throughout the build process. The build platform is within a temperature-controlled chamber, where the temperature is usually a few degrees below that of the material melting point, reducing the dependency of the laser to fuse layers together. The chamber is often filled with nitrogen to maximize oxidation and end quality of the model. Models require a cool down period to ensure a high tolerance and quality of fusion. Some machines monitor the temperature layer by layer and adapt the power and wattage of the laser respectively to improve quality.