"My favourite part was getting to know how film-making is done and meeting and working with all sorts of different people."
Mr Rutherford said he saw more than 50 girls during casting sessions in Sydney without luck.
"It was quite taxing on my time, travelling to audition after audition. I decided to request headshots from casting agencies across Sydney, so that I could at least see if their certain look was what I was after," Mr Rutherford said.
He said most of the names on the list had auditioned to be the Milky Bar Kid and he kept following the YouTube links until he saw this "little blonde girl - confident in front of camera, expressive and eager to perform".
"She was intriguing to watch, funny and had a simplistic innocence which was perfect for the role. You could say it was 'cast' at first sight," he said.
"I felt like I was seeing a star before the earth spun into orbit around her. New Zealand's best kept secret. As an independent film-maker you grab on to opportunities like that. As much as I knew I had found my lead actress, I still had some obstacles to consider. I remember thinking, 'She's perfect. Wait. How long ago was this audition? What does she look like now? Where's she from? That's a funny accent. New Zealand? No - we'll have to fly her over to Sydney. That's going to cost extra'."
Mr Rutherford said 11-year-old Hinetaapora brought a lot of life and was much loved by the crew.
"She was perhaps nervous for about two minutes, and then she was working the crowd into her usual groove. I was amazed at how she could turn from completely mucking about with her co-lead Kai Lewins, into a serious moment.
"The role that Hinetaapora plays in the film is a carefree, imaginative girl, who sees the world as adventurous and follows her heart and curiosity.
"She notices a boy in a classroom after school and becomes intrigued by him, trying to understand why he's so down.
"The boy is everything the opposite of her ... As their conversation draws deeper, their encounter with each other will change their thinking forever."
The former Te Kura o te Koutu student regularly hosts a segment on te reo children's television show, Pukana. She and her family recently moved to Hamilton for her parents' work commitments but she said she loved being in front of the camera and hoped to continue acting in the future.