They contacted Hauraki District Mayor John Tregidga who got in touch with GO Waihi Coordinator Brian Gentil.
"From a supposed flat sign about two metres by three metres it turned out to be a little bit bigger and heavier," Mr Gentil said.
"One and a half metres wide, three metres high, seven metres long and 1.3 tonnes - there was a bit of extra work involved."
With a small budget GO Waihi said it asked the business community to help and they were very responsive.
After the structural engineer's report got signed off, Carters Contractors stored it, moved it and dug the base for the foundations before craning it onto its plinths, which makes it about5m high now.
Brownmore Construction and Firths came to the party with the foundations, concrete and workers, while Duncan Cook and Sel Baker did what builders do best and put all the framework together as the rainbow was raised onto plinths.
Alitech provided all the metal strips for the joins, Mark Spiers Roofing Ltd sorted the rubber and waterproofed it and Warren and the crew at Mitre 10 Waihi came to the party with loads of wood, ply and hardware.
Resene supplied the paint and Trade Sales representative Charlie Skarratt, organised Dave Dudek and the team from Waihi Beach Home Decorators to give the rainbow a fresh coat of paint and a new sparkle.
Hauraki District Council provided safety fencing and advice on safety and Waihi Scaffolding Hire framed it up for the workers to do their job.
"Without everyone's can-do attitude we just wouldn't have been able to achieve this," Mr Gentil said.
"It really has been amazing the enthusiastic response I got from everybody. They didn't hesitate, and I'm so grateful of their support."
Get your picture with the rainbow GO Waihi's Shot of Gold Promotion is still on until the end of October. Take a photo of yourself, your family and friends featuring Waihi's new rainbow, then email it to info@waihi.org.nz, one per email, with your name and contact details and you'll go in the draw to win prizes.
