The plot of The Piano in a Factory is easily summarized: A father makes a piano of steel to win over his daughter from his wife.

The film is amusing and warm, dealing with parental love and friendship, but it was neither easy nor amusing to make.

China's film market, although boasting an annual box office growth of 35 percent since 2003, leaves little room for art films, between domestic extravaganzas and Hollywood blockbusters.

Although the film has been given various awards - best actor at the 2010 Tokyo International Film Festival and four major awards at the 2011 China Movie Channel Media Awards - its box office prospects are uncertain.

It fills the same summer slot as the 108-star-studded Beginning of the Great Revival and the upcoming Hollywood blockbuster Transformers 3.

Despite all the difficulties, director Zhang Meng is optimistic and feels he is a lucky person. "At least the story is one I really wanted to tell," says the 36-year-old.

It portrays a group of factory workers led by the protagonist Chen Guilin, whose estranged wife wants a divorce. Their daughter, a music lover, says she will go with whoever provides her with a piano. Since they are poor, Chen and his friends use the wood from demolished buildings and scrap metal from a closed factory to create a steel piano.

To tell a story about factory workers in Northeast China, the country's former industrial center, where the director grew up, was Zhang's original idea.

"The factory zones in many Northeastern Chinese cities, which had their glory days, have given way to real estate development," he says.

When he returned to his hometown of Tieling, Liaoning province, after graduating from the Beijing-based Central Academy of Drama in 1999, he found laid-off workers had opened small stores in a market, selling steel products.

"They must have been confused about the social changes, but they lived on with optimism and what they had learned during their factory lives," Zhang says.

On the same trip he discovered a wrecked piano on a deserted drama troupe's stage. He was told that his father and some colleagues of the troupe made it themselves.

He had his story.

China Film Pitch and Catch, a program of the Shanghai International Film Festival promoting new filmmaking talents, picked up the light comedy. In 2009 Zhang was offered 300,000 yuan ($46,408).

By April 2010, he had collected 1 million yuan, with the help of his friend Gwak Jae-yong, a South Korean producer. Although the film needed about 5 million yuan to complete, he decided to start filming anyway, fearing the Shanghai festival grant would expire.

The first "financial crisis" arrived just 20 days later. At one point there was a film budget of just 47 yuan left.

Qin Hailu, the film's lead actress, lent a hand. Qin rose to fame in the art house movie Durian Durian, which won her best actress at Taiwan's Golden Horse Awards in 2001. She offered to work without pay and supported Piano's post-production.

"I have been acting for 10 years," Qin says, referring to why she invested in the film, "I know what a good film is."

To their delight, the film won plaudits after previews among critics and peer filmmakers. Director John Woo called it a "warm and touching comedy".

"Zhang Meng surprised me with his original and creative approach, which was perfect," he said after watching the film, which will premiere on July 15.