The body and parts were made from different materials, including alloy and composites, which meant some parts could be paint stripped while others had to be sanded.
"It's all done very, very carefully," Mr Hallowes said.
"If it was a vehicle we could rip into it but the biggest majority is composite and you can't be too aggressive.
"It needs to be sanded and that's been a long process," he added.
Cracks in the paint had started to appear which, if left, could cause erosion.
Mr Hallowes said he had taken careful templates from the other helicopter as they had to look the same.
"Getting all the lines right was real important. They have to look the same when side by side."
The makeover process has included sanding, priming, painting with aviation grade paint before a final clear coat sprayed on to protect the paintwork from the weather and ultra violet rays.
The job was expected to be finished next week.
Mr Hallowes has been helped on the job by his father, and a few others keen to help out with the rescue helicopter. During the summer he flies as a commercial pilot for local company Salt Air.