A custom coffin is being built for the funeral of the world’s longest-surviving conjoined twins, who died on July 4 in the US state of Ohio of natural causes.

Donnie and Ronnie Galyon, who were born joined at the abdomen, claimed the world record in 2014 shortly before they turned 63.

Their younger brother Jim Galyon said he has received an outpouring of support following their deaths.

“They made 68, and they couldn’t ask for anything more,” he said.

A funeral with family and friends is scheduled for next week to allow time to build a coffin large enough for both of his brothers, Mr Galyon said.

On Facebook, he said, people had written to him saying, “‘You gave your brothers a great life”, and that meant the world to me.”

Starting as children, Donnie and Ronnie Galyon appeared at carnivals and on cruises as a sideshow attraction.

Jim Galyon said that their income supported their family for years.

They retired from entertaining in 1991.

In 2010, the twins’ health declined, and the Dayton community raised funds to help renovate Jim Galyon’s home to allow the brothers to move in and navigate in a custom wheelchair, the Dayton Daily News reported.

“Everyone came together to help bring my brothers into our home, which gave them 10 more years of life,” Mr Galyon said.

The brothers died of congestive heart failure.

“Their bodies were tired and it was time,” Mr Galyon said.