Seventeen-year-old Elisha Fleming and Iona Mellor, 16, founded Photo Chainz Nelson in February 2014 to fundraise for the Mental Health Foundation.
The keychains will cost around $4.30 and 50 cents from this price will go towards the foundation.
The project began as part of the Lion Foundation's Young Enterprise Scheme (YES).
Each keychain features one of the foundation's five ways to wellbeing on one side - Connect, Give, Take Notice, Keep Learning and Be Active.
The other side is left blank so people can insert a picture of their own.
Fleming said he had experienced severe depression, social anxiety and other issues in the past, but had recovered with the help of counselling.
"Originally, people thought my depression was just a phase. I'm now over it, but when they say that, it's not helpful for people suffering."
At least two of Fleming's friends have attempted suicide. He said that as a friend, their depression had impacted him deeply as he never knew when the last time he might see or talk to them would be.
Mellor said she had had problems with self-harming. She was committed to supporting her friends through their own struggles with mental illness, but said the ongoing pressure could be stressful.
"There are nights when I'm talking to three of them on Facebook and they're all having suicidal thoughts."
She said mental illness was a subject which had not been open for discussion until recently, and a lot of adults did not understand the full extent to which it could affect teenagers.
The pair both felt that education was the key to improving the situation.
The keychains are available via Fleming and Mellor's Facebook page.