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Wang also explained how his team successfully produced C919 airplane components using 3-D printing techniques. "They wanted to produce a double-curved surface window frame for the airplane, but there is only one European company that can do it. The manufacturing time is two years and the company asked for $2 million to make mold tools ... Time was limited and they turned to us. We completed the whole project in 55 days."

AOD, which was founded in 2013, has a total of 80 employees at its manufacturing center in Shanghai, sales companies in Tianjin and Weifang, headquarters in Qingdao and a research and development base in Beijing. It has gained three rounds of financing.

"But money is still our biggest problem", says Jia Qiuyan, the AOD sales manager. "Big sums of money have been spent on research and development, marketing and branding.

"However, we are very confident about the future because we have several financing projects under negotiation for this year," she said.

Jia's confidence also comes from growing market expectations. "Since the latter half of 2014, I have seen obvious growth in demand from various industries. Inquiries from the Yangtze River Delta are the largest, so are deals with companies in that region," she says.

Lian Ning, in Nanjing, says that in terms of the development, China's 3-D printing technology is rather advanced. "In general, China's 3-D printing industrial players are small, and they are located in different parts of the country," he says.

Lian says there are two main kinds of 3-D printing companies in China: Startups by Chinese who have returned from overseas and are interested in the technology and companies started by researchers at higher education institutions.

"The startups are usually small and the companies owned by researchers usually don't survive, because they don't understand the market," says Lian, who used $5 million of investment funds to start Nanjing Zijin-Lead Electronics seven years ago.