The VintageClub was started in 1958 and continued to expand, club life member Charlie Davis said.
Mr Davis was the main organiser behind the new building and said more donated vintage tractors and machinery meant more space was needed at the West Otago Vintage Museum in Tapanui to display it.
The $120,000 building was built over nine months by Calder Stewart.
Work finished on Wednesday.
The building was funded mostly through community grants, as well as from fundraising by the club.
Club member Roger Brocks said all that was needed now was to have safety checks and consents signed off before the inside display could be finished.
The final display of machinery in the new building also still needed to be organised.
"We're going to rearrange things and there are tractors in the existing part that need shifting,'' Mr Brocks said.
Club members would also complete landscaping and lay concrete slabs outside the building in the coming months.
The museum was opened in 1985, and was first expanded in 1997.
The running of the museum, which is open at weekends, relied on volunteer support from the members of the club, Mr Brocks said.
Club members often engage in vintage tractor "square dancing'', which involves moving their vehicles in time to music.
