Mario Huettenhofer, chief of the German company 3D Fab, presents his own face as 3d print during the international fairs FabCon 3.D and Rapid.Tech in Erfurt, Germany, Thursday, May 15, 2014. 130 exhibitors from all over the world present the entire world of 3D printing. The trade fairs are accompanied by specialist programs featuring 80 scientists, practitioners and trend analysts from ten countries, who will explain the latest findings, trends and applications for additive processes in industry and for 3D printing in the private sector to newcomers, experts and consumers alike. (Photo by Jens Meyer/AP Photo)

Dancers prepare before a performance in the backstage area of the Buick exhibition during the “Auto China 2014” Beijing International Automotive Exhibition in Beijing on April 21, 2014. Leading automakers have gathered in Beijing for the kickoff of China's biggest car show, but lackluster growth and environmental restrictions in the world's largest car market have thrown uncertainty into the mix. (Photo by AFP Photo)

Robert The Bruce's army from The Clanranald Trust during a rehearsal for the Battle of Bannockburn re-enactment performance which will be staged at the Bannockburn Live Event in Bannockburn, the 700th anniversary of the battle, on June 27, 2014. (Photo by Andrew Milligan/PA Wire)

India's Border Security Force (BSF) “Daredevils” motorcycle riders perform during a rehearsal for the Republic Day parade on a foggy winter morning in New Delhi January 8, 2015. India will celebrate its annual Republic Day on January 26. (Photo by Ahmad Masood/Reuters)

Mechanic and welder Sergei Kulagin, 32, strengthens the bracing of a spider sculpture, made by Kulagin, during a demonstration on the wall of an automobile repair workshop in the town of Divnogorsk outside Krasnoyarsk, Siberia, October 15, 2014. Enthusiast Kulagin, who works as a mechanic of an automobile service station, created about 20 sculptures made of used car parts and components during his non-working hours. (Photo by Ilya Naymushin/Reuters)

“Winter shapes, Moscow river”. Moscow river at this part is never covered by ice. When the temperature is very low it's possible to see a strong fog. Morning light and pipes of the oli factory creates a fantastic landscape. Photo location: Moscow, Russia. (Photo and caption by Sergey Rumyantsev/National Geographic Photo Contest)

“Hippo Chase”. As we approached the camp the Selinda Reserve of northern Botswana our boat passed by a hippo resting in the water. I turned around to look back at the boat's wake and saw the hippo charging after us! The hippo must've been tired from an all-nighter because he was angry. He rose way up out of the water three times trying to chase our boat! He was coming at us with such force that he created a wake of his own. Photo location: Selinda Reserve of northern Botswana. (Photo and caption by Curtis Simmons/National Geographic Photo Contest)