Number six plastics were typically meat trays or the types that stored food from the supermarket deli as well as yogurt pots.
"The yogurt containers, they're white, so you'll end up having a white background. They shrink 50 per cent. It condenses it and fixes the sharpie or coloured pencil into the plastic."
The group made broaches, key rings and buttons, but Coffey said they could be used for art projects in general.
To manipulate the plastic they used a heat gun, the type typically used to help peel paint off of walls.
Téa McMenamin-Wood and Lucas Briggs were both creating their own pieces of art.
"We're just drawing on these pieces of number six plastic," said Lucas.
"We're going to shrink it so it's a lot smaller and it should give it a bit of waviness and a bit of texture.
"It's my first time being here and so far I have really enjoyed it."
The art session with Julz Coffey was part of a number of Plastic Free July activities being held at the Resource Recovery Centre.
This morning there will be worm farming lessons for children with the centre's environmental education officer, Anna Dawson.
Tomorrow there'll be an information session on nutrient rich food as well as a fruit tree giveaway.
That's followed by a winter workshop on Thursday (10.30am-1pm) and an Art & Science Lab on Friday (9.30am-11am).