Detective Senior Sergeant Tim Leitch said it showed P-labs could be set up anywhere.
"The police kind of tripped upon this lab - we didn't realise there would be a lab there, so we weren't prepared for a lab," Mr Leitch said at the time.
At the High Court on Monday, Detective Sergeant George Campbell said the 1.2kg find of methamphetamine was a significant reduction of harm, Fairfax Media reported.
The Crown said three parcels of methamphetamine had been brought into New Zealand disguised by adding plaster and dye in July and October 2013 and February 2014.
But the defence said there was no evidence of what was in the parcels.
Chea was described as a "charismatic" man in court who had methamphetamine convictions from 2011 and Dao was described as his assistant.
Both men were found guilty on two charges of importing methamphetamine, possessing the drug for supply, supplying the drug and four charges of receiving stolen property.
Debreceny, a car repairer, was alleged to have helped organise the delivery of the parcels.
He was found guilty of one charge of importing methamphetamine and Cummins was found guilty of possessing the drug for supply.
The group are all due to be sentenced on July 31.