The Olympic Cauldron was crafted at a place that looked like James Bond's gadget workshop, the designer Thomas Heatherwick said on Saturday.
He was pleasantly surprised when the idea to have 204 separate petals in 10 rings to come together to form one cauldron and a single flame got the go-ahead from a range of officials including Prime minister David Cameron and London 2012 chairman Lord Coe.
This is because "it is the most moving parts that are humanly possibly" to have in a cauldron.
The copper petals, created to be "very small and humble objects", were made using traditionally skilled craftsmen of the sort who used to roll sheet metal to make body parts for car makers such as Bentley, according to Heatherwick.
Seven rising stars of youth athletics were picked to light the flame
He said: "It is like the biggest gadget that anyone can make in a shed but this shed is the most sophisticated shed in Harrogate.
"It was like the Bond gadget workshop."
The rods which make up the stem of the cauldron are made of stainless steel with a heat and acid treatment that makes it a colour called bad black, which is actually slightly blue.
The petals are copper and the entire structure is about 8.5 metres tall and will be moved from the centre of the stadium overnight tomorrow.
The petals, lit, rose together
It will move to the end of the stadium where the huge bell was struck to signal the start of the opening ceremony.
The cauldron design team used the fact that the athletes' parade is a long event, lasting at least 90 minutes, to retrieve the elements from the centre of the parade and discreetly fix them to specific spots on the cauldron.
Practice had to be done at night as the lighting of the cauldron had to be kept secret.
Rehearsals were held in the north of England but were switched to the stadium nearer to the grand event.
The individual stalks rose to form one enormous cauldron in the middle of the stadium
Heatherwick said: "It had to stay a secret. We had to wait until the dancers had gone home so it was about 3am - that was the time that it (the stadium) was available for use to use."
The seven teenage up-and-coming athletes who made up the final torchbearers had 45 seconds to light the cauldron. There was then a 45-second wait before it all lifted into place.
By the time the first ring was in place the last one was lifting and coming together. "So it was like a dandelion seed being blown - but it seemed to work, which was a huge relief," Heatherwick said.
Heatherwick said he and artistic director Danny Boyle, the mastermind behind the opening ceremony, wanted something that was not about being bigger than the last Olympic cauldron, in Beijing, but was about the people involved in bringing it together. This is one of the reasons why is was set in the centre of the stadium with the parading athletes surrounding it.
He said: "We were thinking about this incredible object with 204 nations coming together. It was a challenge but it did not feel enough to design a different shaped bowl."
The cauldron will be split up at the end of the Games and each piece will be returned to a competing national Olympic committee (NOC).