The 16m cardboard tube is a replica of those being used to construct the new Christchurch Transitional Cathedral and has been brought to Dunedin to raise funds for the project.
"It's exactly the same as the ones they're building the Christchurch Cathedral with," the Dean of St Paul's, the Very Rev Dr Trevor James said yesterday.
"We are showing solidarity with Christchurch with this exhibit.
Although when they asked, I hadn't understood how big it would be," he said.
"I am delighted we can support Christchurch in this way. The temporary cathedral, while controversial, is a vital first step for the church and people in Christchurch."
The 700-seat Transitional Christchurch Cathedral, designed by Japanese architect Shigeru Ba, will be built on the corner of Madras and Hereford Sts in April.
The Christchurch Cathedral was extensively damaged in a 6.3 magnitude earthquake on February 22, 2011.
The temporary structure will serve as a place for community worship and gathering until a new, permanent cathedral is built.
It will incorporate 98 of the cardboard tubes, timber beams, structural steel and a concrete pad and is designed to last for more than 20 years.
The fundraising tube will be at St Paul's Cathedral for a week.
Fundraising tubes are also on display in Auckland, Napier and Wellington.