By Soutik Biswas BBC correspondent in Bombay

They blow up buildings and cars, create rain, storms, smog, smoke, fire, confetti and rig up explosions and organise stunts.

Bollywood's Shah Rukh Khan feels the heat of digital flames

But today the 500 or so movie effects artists are a despondent lot.

With Bollywood cinema becoming slicker, special effects shops have sprung up all over Bombay, taking away a lot of their business.

The shops' computer-generated effects have become the mainstay of Bollywood action.

Dwindling income

Arun Patil is the president of the special effects men's trade union, the Movie Action and Dummy Effects Association.

He spent two years with 20th Century Fox in Los Angeles, learning the ropes of setting up effects.

The manual, mechanical part of movie effects is dying out Rajiv Agarwal, owner, Rajtaru graphic design shop

He also worked on a Bollywood film called Burning Train in the 1980s - Bollywood's first big-effects-crammed disaster movie in which he helped set an entire moving train on fire.

That was then. Now Mr Patil is having a hard time keeping his flock happy as their work dries up and incomes dwindle.

"Computer-generated graphics are clearly the future. Our work is in decline, though we still are not totally out of work," he says.

Average monthly incomes for the effects artists have dwindled to about 5,000 rupees ($100) in a good month.

Hazardous conditions

But even though computer-generated effects are now the new buzzwords in Bollywood, few film-makers have a clear idea of what they want from the new effects shops.

One of the most thriving shops in Bombay is Rajtaru.

Arun Patil says his fellow manual effects artists are seldom feted

The 10-year-old company employs 70 graphic designers and editors who are inundated with work.

Film-makers flock to Rajtaru to digitally enhance their films, add special effects and do up snazzy credits.

"The manual, mechanical part of movie effects is dying out simply because we can do a lot of things on the computer much more easily," says Rajiv Agarwal, one of the owners.

So much so that his shop even burns down a house digitally in an upcoming film starring Bollywood star Shah Rukh Khan - a job that the manual effects people would have done even a few years ago.

In another upcoming big budget action film shot in Russia, the effects shop manages to burn down an entire city after building miniatures and digitally torching them.

These are not happy tidings for the manual effects people, who feel they have been cheated and underpaid most of their working lives.

Most of them are untrained workers who learn on the job. They continue to work in potentially hazardous conditions with no industry-backed life insurance cover.

For example, the effects people who work rigging small explosions usually do their preparations in their homes in the absence of a safer place.

Last August an effects artist, Dilnawaz Khan, died in a blast while mixing explosives in his cramped Bombay home.

Many effects artists feel they have been cheated and underpaid

Four other family members were also killed.

Ghulam Ghaus, 52, a manual effects worker who has been in the industry since 1979, says business has never been so bad.

"There is very little work these days and even the Bollywood cinema has changed so much that they don't need our help any more," he says.

"There was this long season of love stories that killed action movies. Now there's a trend in police stories, which require some action. Then they will get back to love again!"

The effects artists also complain that the industry's leading stuntmen - called "fight masters" in Bollywood speak - are taking away their work by setting up their own stunts and effects workshops.

The effects workers say they do a dangerous, thankless job and get very little in return, including recognition.

"During the film awards, the computer-generated design people are feted. No mention is ever made of our contribution," says Mr Patil.

To bolster their profile, the manual effects workers have now produced a low-budget video showcasing their talents.

But clearly, as Mr Patil agrees, they will continue to become marginalised in the fast-changing world of Bollywood.