Mr Gray said conditions imposed by the major funders called for 100 per cent of the building cost to be on hand before a start could be made on the redevelopment.
With about $150,000 still needed, people and businesses who had pledged support were now being asked to "formalise their donations" and a new round of applications, including approaches to all three district councils in Wairarapa, were being prepared.
"All donations, small or large, really do matter as we strive to get our funding in place," Mr Gray said.
Mr Gray said the museum committee knew from the moment the redevelopment plans were mooted that it would be a "big ask" but the redevelopment of the front entrance was being done with an eye to the future and to complement the remainder of the museum complex.
He said Cobblestones was attracting visitors from a wider and wider range and, by forging close links with Destination Wairarapa, busloads of visitors to the museum had increased three-fold since November 2011.
The redevelopment of the entrance will include exhibition space for significant objects in the Cobblestones collection and audio-visual and interpretive displays telling the stories of Wairarapa's early settlers.
The project will be the largest heritage makeover in South Wairarapa since the redevelopment of Greytown Town Hall to create the Greytown Town Centre.
Concept designs and plans for the new work were drawn up by Accent Architects.
The Cobblestones Trust commissioned the architects with a brief that would guarantee the new building work was in keeping with the heritage nature of other heritage buildings on-site, would have striking street appeal and be welcoming to visitors.
