There were spare blocks of stone at Takaro Park and, after inquiring whether it was possible to join in, she started carving later that day, with a clear idea of what she wanted to create.
Ms Ellis has always loved Oamaru stone and thought she would "give it a shot".
She wanted to make a sculpture that would hold precious pieces of pottery she has collected.
The shape of her sculpture was not intentional - "it fell out of the stone" - and she was loving the experience.
As a keen gardener, she had plenty of upper body strength.
The other sculptors were "absolutely wonderful" and supportive and there was a nice flow of visitors to the park who stopped and chatted.
Ms Ellis said she would definitely continue carving at home once the symposium had ended.
"To get the ability to pull a form out of the stone is what I'd love to do, because it's amazing how many different forms a shape can take."
The Oamaru stone symposium will culminate next weekend with entertainment and a silent auction of the art works.
