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The "Byfusion" machine has been 10 years in the making, but a working prototype at the Green Island landfill can swallow most types of raw plastic and turn it into compacted plastic bricks or other shapes.
The plastics - from drink bottles to meat packaging - went in one end of the cylindrical machine, which washed, dried and compacted the plastic, Mr Lewis said.
A brick emerged every 30-45 seconds, with each formed from 10kg of plastic.
The rock-hard bricks could be used for garden retaining or landscaping walls, and had other potential uses including shock absorbers behind crash barriers.
Consideration was being given to using the products to build hurricane and tsunami shelters in the Pacific Islands, or cheaper sustainable housing where wood was scarce, he said.
Dunedin-born Mr Lewis developed the machine while living in Queenstown a decade ago, but mothballed the project after failed attempts to market it in the United States in 2001 and Christchurch in 2003.
The machine was "ahead of its time" then, but he hoped it was now a viable solution to the piles of plastic flooding into New Zealand landfills.
Mr Lewis and his company, Bale Fusion Ltd, dusted off the project this year after being approached by Dunedin City Council solid waste manager Ian Featherston.
Mr Featherston said he stumbled across Mr Lewis' project while reading a waste management trade magazine.
He worked with the council's economic development unit and Dunedin's Business for Change cluster to bring the project south.
The council offered a $20,000 grant to help cover setup costs - paid for by a Ministry for the Environment waste minimisation levy - and cluster members also offered financial support.
Once fully operational, the machine would help the council meet waste minimisation targets and find alternative uses for some types of plastics - numbers 3-7 - that lacked lucrative recycling markets.
There would be "synergies" with the new recycling plant being built at the Green Island landfill.
It was hoped supporting the business would bring economic benefits to the city.