The nacelle is known as the part of the engine that functions as a sleeve and allows it to decelerate, de-ice, channel air, contain debris, and more. Generally made of carbon fiber today so that they are light in weight, the nacelle offers challenges for manufacturers. Companies such as GKN Aerospace are currently investing in additive manufacturing, along with creating powders for printing with metal. Not all within the industry are convinced that the expense will justify the means however, as all will wait to see if nacelles become more durable thanks to AM techniques. Read more at 3DPrint.com: https://3dprint.com/164699/am-in-nacelle-production/