The world's biggest statue is finally taking shape on a hill overlooking Bali's international airport.

Twenty-five years and around $100 million in the making, the enormous copper and brass sculpture is of the Hindu god Wisnu astride the mythical bird Garuda.

Garuda's concrete and steel skeleton. ( ABC News: Adam Harvey )

After years of planning, re-designs, cash shortages and stop-start construction, sculptor Nyoman Nuarta says the project should be finished next September.

And the final phase — the fitting of the sculpture's skin to the concrete and steel skeleton — is well underway.

The copper and brass claws of Garuda are finally gripping an enormous, purpose-built, concrete pedestal.

It should be relatively straightforward, compared to the complex engineering and fundraising for the private project.

"I no longer think about making profit from this project but I just want to work and finish this project because this is my dignity — my family's and mine — that's at stake. So it has to be completed," said Mr Nyoman, speaking to the ABC at his workshop in Bandung, on the island of Java.

Sculptor Nyoman Nuarta says he wants to finish the project because his dignity's at stake. ( ABC News: Adam Harvey )

"Garuda Wisnu Kencana" is about 75 metres high — 120m if you count the pedestal.

That is about 30m higher than the Statue of Liberty, off New York. But Liberty is tall and thin, while Garuda is almost as wide as it is high — its wingspan is 64m.

That has made life complicated for the project's engineers. They do not want this Garuda to actually take flight.

"We've designed this statue to last for the next 100 years," construction chief Apul Sihotang said.

"We did wind tunnel tests in Canada, where we calculated the maximum velocity of the wind which will happen in 100 years.

"We have anticipated the wind velocity."

The head of Hindu god Wisnu, before the copper and brass skin is applied. ( ABC News: Adam Harvey )

Strong winds are slowing the installation of the copper and bronze panels — the crane cannot operate if the wind blows more than 10 knots.

Garuda's shape is so complex that engineers have designed special joints in the supporting structure, with up to 11 enormous steel girders coming together at the same point. Normal construction joints have four or six girders.

The specially-designed 11-way joint for Garuda Wisnu Kencana. ( ABC News: Adam Harvey )

The sculpture's unusual shape also means that maintenance workers will not be able to reach the outside of statue.

"Repairs will be done from inside the statue. We will build a catwalk to fix the statue from the inside so when there is a damage, the statue will be cut out to be fixed from the inside," the construction chief said.

The statue is being built by Mr Nyoman's team in Bandung, on the island of Java. It was made in wax, then fibreglass, then copper, then brass, then cut up and driven by truck to Bali for final installation.

Mr Nyoman, who is Balinese, says the project is important for the island.

"We know that Bali thrives from tourism and culture. If we don't develop the culture it will disappear one day," he said.

"So we have three responsibilities: to preserve the culture, develop it, and find new alternative cultures."

A model of the mythical bird Garuda's head. ( ABC News: Adam Harvey )

The project is important for Indonesia, says one of the people behind the project, Ida Bagus Gede Budi Hartawan.

"Culture is a big thing for our country, our civilisation. When we talk of technology, we may not be there yet. When we talk of economy, we may not be there yet either. But when we speak of culture, we can be equal," Mr Gede said.

"The latest and greatest masterpiece that this nation has is Borobudur. After that old generation, this nation never produced such creativity again.

"In the global community they underestimate us because of the violence here.

"Thus it is our goal to build something grand for our children and grand-children, for our generation and for the world."