When the Otago Regional Council introduced a new bus ticketing system earlier this month, the Go Cards became redundant.
Rather than let them go to waste, Kavanagh College head of music Georgie Watts had an idea.
She put out a call for the cards and has turned them into guitar picks for pupils.
"We know there’s going to be a lot of cards that are available," Ms Watts said.
"I just want to make use of them."
Ms Watts uses a "pick punch" — like a hole punch — to cut out the picks and then files down the edges so they do not damage guitar strings.
Beforehand, she checks there is no remaining balance on the cards, and gives the money to charity if there is.
So far she had been given about 15-20 cards but that was "slowly picking up".
Year 8 pupil Anamika Jones said she was happy with the recycled picks.
"They feel like just a normal pick, really."
Guitar picks were often in short supply and many pupils used their own, Ms Watts said.
"It does not matter how many I get," she said.
"I will get through all of them."
School pupils were encouraged to drop their cards into a box in the main office, or give them to their tutor.
"There’s got to be a few extra Go Cards around."
