'Peasant Da Vincis' on show in Shanghai exhibit

The movable metal fins on Li Yuming's homemade submarine are designed to make it swim like a fish, but with no engine it cannot go forward or even return to the surface once launched.

"Minor problems," says the Chinese peasant inventor, who insists funding is all he needs to make it functional.

Like a giant rusty goldfish, Li's two-metre-long metal submarine hangs in the air at Shanghai's Rockbund Art Gallery, surrounded by planes, helicopters, flying saucers, and other 'Peasant da Vincis'.

The collection is a new exhibition by Chinese artist Cai Guo-Qiang, whose gunpowder on canvas designs won the Hiroshima Art Prize for peace and whose fireworks for the opening of the Beijing Olympics dazzled the world.

Cai was fascinated by the humble handcrafted charm of the whimsical inventions by Chinese peasants - robots, flying machines and even an aircraft carrier - which he said were "borne out of a desire to escape the gravity of one's circumstances".

"I was very touched by their uselessness, like the submarines. Once they sink they can never float back up," Cai said. "It's the same with artworks, they're pretty useless, but everyone takes them very seriously."

The idea of combining the inventions with his own art in halls featuring grass and chirping birds sprang from an exhibition he curated for the 2005 Venice Biennale that included peasant Du Wenda, 44.

Obsessed by flying saucers since seeing a copy of Science Fiction magazine at the age of 10, Du had hoped to fly one of his homemade craft at the show.

But Cai said it soon became clear that if it did fly, he would be unable to land and the homemade craft would fall apart. He consoled Du, who feared he had shamed his nation.

"It's not a big deal," Cai recalled telling him. "The world has the highest respect for Italian inventor Leonardo da Vinci, but none of his inventions were ever completed."

Now Cai and his peasant collaborators are providing a counterpoint to the slick presentations nearby at the six-month, multi-billion-dollar Shanghai World Expo.

Peasant inventor Wu Yulu, 48, took over a gallery floor, turning it into a robot workshop where two creations paint dots and splashes in the style of Damien Hirst and Jackson Pollock.

Other robots jump, dance and pull a rickshaw.

The stories of the inventors such as Wu - who hopes his robot offspring such as Big Wu, Second Wu, and Third Wu will lead to fame and fortune - are as captivating as the creations.