They started with an idea Bill and Mike Osborne had 30 years ago. The two wanted a Ngati Tuera/Ngati Hinearo community around the marae, as there was in the past.
Mr Mair said Ngati Tuera had a determination gene, and were making the vision happen.
"If you say 'no' that means 'yes' to us."
The trust's first two houses are already occupied, the first one by Mr Potaka's 93-year-old father, Peter.
The newest house is 147sq m, with three bedrooms, a woodburner and gas stove. Its floor and ceiling are insulated, it's double-glazed and should last 100 years.
It cost $240,000, with 75 per cent paid by the Government's Social Housing Unit and the rest by the trust. Te Puni Kokiri made a contribution, and there was early help from the former Community Employment Group.
The trust will be taking care of landscaping and roading, and the workers were subsidised by Work and Income New Zealand.
The building blocks are made of pumice, mined on trust land nearby and mixed with cement. They were made at a site close the the river. Some washed away in a flood and others had to have silt washed off them.
There are more blocks ready for building. Mr Potaka said the trust's next house will be at Kaiwhaiki, and after that some may be built in Whanganui.
"Our aim is to find the money to build a little village like this in town."
The trust helps its own people first, but could eventually build houses for others. The four existing houses used 20 tonnes of pumice and it has enough pumice left for 50 more.
Mr Potaka also manages four land blocks for Heeni Investment Co. There's 30ha of pine forest on the River Rd, a 15ha bee enterprise at Kai Iwi - with manuka planted, and the leased 1400ha beef and bee farm at Paetawa. It also owns 65ha at Rahotu, which is leased out to a dairy farmer.
Mr Mair said it was fantastic to see a third house completed at the marae and the hapu had a long-term economic vision.
"We have got to set in place something for future generations. Our uncles and aunties wanted an economic vision. We are just beginning to get there. It's been a pretty tough journey at times."