The blue, air-conditioned, wood-trimmed, steel carriages with large side and overhead windows will run on the TranzAlpine route, between Christchurch and Greymouth and the TranzCoastal route between Christchurch and Picton.
The workshops have completed the shell of the first of 17 new carriages which are part of a $39.9 million project.
Also part of the contract is a carriage with an open-air viewing platform built to a higher safety standard than those used at present.
Hillside's acting site manager Andy Bisset said the project began about a year ago.
The carriages were designed by KiwiRail mechanical design staff in Wellington and between 60% and 80% of the manufacturing was being done in Dunedin.
The main component not manufactured here are the forged steel wheels and axles imported from Australia.
KiwiRail marketing communications manager Nigel Parry said the contract was awarded to Hillside after KiwiRail "had a look at the world market".
"We did look at the best way of building these, the most cost-effective way of building them, and the best people to do it.
"And it turns out that the best people to do it were the people here in New Zealand."
Mr Parry said the two tourist routes catered for about 250,000 people a year - more than half from overseas.
He said the carriages would run on "smooth ride" bogies and had more than 53sq m of glass, so passengers got a good view out both sides.
The carriages will have GPS-triggered announcements and displays and commentary at each seat in a choice of five languages - Mandarin, Japanese, German, French and English.
The carriages will be completed by December next year.
Mr Parry would not comment specifically on what work Hillside would undertake then.
"We've got a number of other projects on the go.
"Between now and then we're actively looking for more work; more projects.
"It's too early to make the announcements."
KiwiRail has been criticised in recent weeks for not allowing Hillside to tender for the construction of 38 three-car electric multiple units (EMUs) and 13 electric locomotives - part of Auckland's $500 million rail upgrade.
Labour Member of Parliament for Dunedin North Pete Hodgson, who was one of about 40 on yesterday's tour of the workshops, said it was "disappointing" Hillside was not able to tender.
The more important question, however, was whether the KiwiRail tender documents would "give weight" to an amount of New Zealand content.
"I'm hoping they will. We've certainly asked KiwiRail to ensure that they do."
