Project action team leader Andrew Garratt said he was "very confident" the rest of the money could be raised, "as long as the community helps to make it happen".
"This is a plea, yes. Would you like a photo of me on my knees, begging?" he said.
The team behind the mammoth fundraising effort comprised all volunteers: A core group of 12 who met once a week, backed by about 30 active volunteers and another wider circle of businesses donating services to the cause.
Mr Garratt said it was "poignant" to realise it had been a year since the public referendum which gave the project the go-ahead.
"We've achieved a lot, we've set up a really good team ... if this team can't achieve it then no team could," he said.
Criticism of the controversial building seemed to have largely died, Mr Garratt said, but it had been his group's policy to meet sceptics with positivity.
"Occasionally some of our volunteers have found [the criticism] discouraging, but the core group have not been affected by that at all ...
"We don't want to respond negatively. We also acknowledge that people are allowed their opinion and we welcome that," he said.
While fundraising, the team were also planning how to actually build the complex structure. The Hundertwasser's seed or folly structure, Te Kakano, is currently under way at the Town Basin.
Money raised so far included $2.97 million set aside in Whangarei District Council's Long-Term Plan, needed to strengthen the existing building, $4 million from central Government, $1 million from a trust, and about $2.2 million from Whangarei donors. The $16.25 million total figure also covers $1.1 million already spent on WDC on consent for the project, prior to it being taken over by trusts.
People could learn more about the project, get an event schedule for Hundertwasser Month and donate at yeswhangarei.co.nz or by visiting Hundertwasser HQ at 44 Cameron St.
