Going for a song: The tiles of the A2 sail of the Sydney Opera House - 125,000 of them - are looking for new owners. Photo: Kate Geraghty

They are the 12 centimetre by 12 centimetre ceramic squares that, in their own small way, ''embody the ambitions of a nation''. On Monday, 125,000 of the Sydney Opera House's 1,056,006 tiles go on sale as part of a drive towards community ownership of the building's future.

The Own Our House initiative hopes to generate $15 million towards the House's ''decade of renewal'', and launches just weeks after its 40th birthday.

''This building embodies our ambitions as a nation and we thought we needed to do something that really makes people feel: 'My God, I want to be part of it,' '' chief executive Louise Herron said.

Buoyed by the momentum from the House's 40th birthday, Ms Herron and her team is asking the public to spend $100 for a shiny ''ice'' tile or $400 for a matt ''snow'' tile for a 10-year custodianship.

With the entire face of the most prominent, A2, sail to sell, the task is not a small one.

''The reaction that we've had has been pretty wild and enthusiastic and energetic,'' Ms Herron said. ''But it's a lot of tiles. That's a massive undertaking and who knows how it will go.''

At ownourhouse.com.au, users can view the Opera House up close, zooming into the fiendishly complex geometric lattice of tiles, in chevron groupings. There the public can buy tiles, then, as ''housemates'', see the view from their new purchase and add photos and 140-character messages to the virtual version of their tiles.

The idea has been in the making for close to two years, at first stymied by the mammoth technological difficulties of accurately mapping the intricate roof.

A turning point came in June, when the international 3D scanning project the Scottish Ten delivered its first 3D laser-scanned digital model of the Opera House.

The group measured 13 billion points of the building, exact to within six millimetres, as part of a project to digitally map 10 world heritage landmarks, and Own Our House became possible.

Money raised will be used alongside $13.7 million from the state government towards a masterplan that will take the Opera House into its next era. The content of those plans will come into focus, Ms Herron said, if tile sales ''go off''.

''Depending on the level of support, we'd like to run a lot more free programming. We'd like to improve our digital initiatives and our education initiatives,'' she said. ''If it does go off, we'll have big, bold plans to spend the money and we'll be taking people every inch of the way, because it's their money and its their House.''

As much as community goodwill is likely to carry the project along, it helps, too, that Hugh Jackman has already bought 11 tiles and Glen Hansard 15. Jack Thompson, Josh Pyke, Delta Goodrem and Matt Moran have all added their faces and messages to digital versions of their tiles.

And there is the added - and crafty - benefit of the sale's timing. ''We reckon it's a great Christmas present,'' Ms Herron said.