The group decided to come up with an environmentally friendly replacement to plastic bags, she says.
"Everyone uses bags every day. If we can get people to swap from using plastic bags which are sometimes only used once then thrown away, to a bag which can be reused many times, then we can help reduce the amount of plastic bags ending up in our oceans."
With this month being known as "plastic-free July," when people around the world are encouraged to swap single use plastic bags for environmentally friendly alternatives, Katelyn says she thinks the bags will sell well.
"The bags are useful, help solve a worldwide problem and look great too."
The students came up with different phrases to put on the bags, each one carrying an environmental message. One of the designs uses a stylised whale tail drawing, designed by a fellow student at their school, Trinity Kumeroa.
Interest in the bags was high at the company's official product launch last week, which took place at St Mary's Diocesan School hall, and orders are still coming in, says Katelyn.
"When the project is finished, we will be donating 10 per cent of our end of year profits to Project Jonah, so there is a really good incentive to get lots of orders coming in."
Each member of the group has specific responsibilities in the company, from marketing to finances and Katelyn says they have all learned a lot already from the process.
"It is good because we learn about all the different parts of running a successful company, from good communications and marketing through to making sure we are doing well financially."