"We design and build them from scratch. For example, we have our own design of road broom with its own unique hydraulic system, and we can adapt snow ploughs on to the mounting.
"A lot of this stuff has been created, not through creative brilliance, but just from listening to what our customers want."
AES builds truck bodies for a number of major corporates and was a preferred supplier for Downer nationwide.
Neville Stokes, Downer's national plant category manager, said he commissioned most of the company's New Zealand truck builds from AES because of consistent quality.
"We have lined up as a business partner with them and they are our body builder of choice," he said.
"Over the years, we've developed good, fit-for-purpose vehicles they can produce for our type of requirements."
AES machinery division's main focus was on converting dirt-digging excavators into forestry processing machines.
Mr Shultz said: "We essentially completely dismantle the excavators, chop them into bits, and then reassemble them with heavy-duty guarding."
Modifications can include building a heavy-duty forest cab, modifying the booms and dipper arms, and repositioning hydraulic ram mountings.
The company also imported a couple of brands of attachments, which have a range of uses, including mulching, as roading stabilisers or stone crushers, and in agricultural applications.