A seriously ill toddler has fulfilled his dream of becoming a superhero for a day, with a drive through Brisbane in a Queensland-built Batmobile with Batman by his side.

Eli Vale, who turned three on Thursday, was picked up at Ronald McDonald House in South Brisbane and driven to East Brisbane where he was greeted by waiting family and friends from across the country for a surprise party.

The Batmobile, a replica of the 1989 Batman movie car, was built in Toowoomba. ( ABC News: Patrick Williams )

The toddler was diagnosed with ectomesenchymoma, a rare and aggressive form of cancer, in November 2016.

He and his mother moved from the family's home in Gladstone for Eli to receive treatment at Lady Cilento Children's Hospital, where he has been for the past seven months.

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Family friend Joel Herbert said Thursday was about creating special moments with his family and friends.

"It's all about the memories, because we don't know essentially how long we have," Mr Herbert said.

Eli has been in hospital since late 2016. ( Supplied: Gofundme )

"The Batmobile makes perfect sense, we call Eli 'the little super hero' because he's so strong.

"A lot of people have flown a very long distance, Victoria, New South Wales, north Queensland and central Queensland ... his little brother, sister and cousins were there."

Mr Herbert said Eli's diagnosis came on fast.

"He had some constipation and went to see the doctor. They had some scans and within 24 hours he was in Rockhampton Hospital, and within another 12 hours he was flown to Brisbane. It happened very rapidly."

Last month Eli finished his first bout of chemotherapy and had an operation to remove most of the cancer.

"He's back on chemo now and radiation as well," Mr Herbert said.

"We're very, very hopeful but they've obviously been told to expect the worst as well. We're just taking every day as it is.

"The worst time of this is still ahead."

Eli also received a bag of presents from the Dark Knight. ( ABC News: Patrick Williams )

Batmobile builder plans to use car for good

The Batmobile, a custom build of the vehicle made famous by Tim Burton's 1989 movie Batman, was built by Toowoomba man Craig Blackburn and his three sons.

He estimated it took them more than 4,000 hours to complete it over 18 months.

Jeff and Eli Vale pose for a photo with Batman, AKA Craig Blackburn. ( ABC News: Patrick Williams )

Mr Blackburn, who dressed up as Batman for the day, said the original aim was to build the car for his son Shaun's Year 12 formal.

Now he wants to use it to brighten up the days of young fans.

"That's what we want to do ultimately ... put smiles on kids' faces who are struggling," he said.

"It's all well and good to accept money and take adults for a ride, but we really want to help those who are struggling to fulfil some of their dreams."