Three men have been found guilty of conspiring to prepare a Christmas Day terrorist attack in central Melbourne.

Hamza Abbas, 23, his cousin Abdullah Chaarani, 27, and friend Ahmed Mohamed, 25, were found guilty in the supreme court on 2 November of acts in preparation for an attack targeting Federation Square, St Paul’s Cathedral and Flinders Street Station in December 2016.

The verdict, made public on Wednesday after legal delays, followed seven days of deliberations and eight weeks of evidence including from Hamza’s older brother Ibrahim Abbas, 24, who confessed his involvement to police and pleaded guilty earlier this year.

Mohamed and Chaarani laughed and smiled at each other as their verdicts were read. Mohamed gave his family a big grin while Hamza gave them a thumbs up.

Police left court carrying two machetes bought by Chaarani and Ibrahim in preparation for the attack.

The group also had the makings for pipe bombs - sparkler dust, hundreds of match heads and chemicals including hydrogen peroxide - that were intended, as Ibrahim put it, to “wage violent jihad”.

They got the recipe from the infamous al-Qaida magazine article “How to make a bomb in the kitchen of your mom”.

Ibrahim revealed during the trial that he believed it was “fine for me to kill Australians” because Muslims have been killed in wars involving Australia.

“It’s not hard to kill a person with a machete. It just takes one slice to the neck,” he said in his police interview.

The plot was foiled on 22 December, 2016, by police who had been listening to their preparations and watching as they carried out reconnaissance at Federation Square.

During his arrest, Chaarani asked police to “make me a martyr”, officers revealed.

In Hamza’s defence, lawyer Felicity Gerry QC argued he was a “fishbrain” and the “idiot brother” who could not be trusted to know details of the plot.

Hamza joined in December 2016, but plans between Ibrahim, Mohamed and Chaarani had been afoot since at least October.

Mohamed and Chaarani had tried in 2015 to go overseas and fight with Islamic State.

Chaarani said he wanted to “follow the same path” as Hamza and Ibrahim’s cousin Nabil Abbas who, it was revealed during the trial, had died fighting with the terrorist organisation.

Hamza, Mohamed and Chaarani will face a plea hearing before being sentenced.