The boy, who cannot be identified for legal reasons, has pleaded not guilty to acts in preparation for a terrorist attack and is facing trial in Brisbane Supreme Court.
He is accused of planning to use pipe bombs packed with nails to attack Liberal Party members and the Labour Day March in Brisbane to promote beliefs he shared with America's notorious Unabomber.
The teen's research and purchases for making homemade explosives were not in dispute but his intent and thinking at the time would be an issue at trial, defence barrister Laura Reece told the jury on Tuesday.
"He kept a diary of his innermost thoughts… you may gain some insight into his state of mind from his own words," Ms Reece said.
"He says 'I think I've gained an autistic interest in bombs but it's going to be tough to shake it off'."
Ms Reece said he was 14 while struggling with personal and family problems when he first started discussing explosives.
"He also wrote about his feelings on suicide, being lonely and how he thought he was missing out on some things in life because of his autism," she said.
The boy was about to turn 16 when he rode his scooter around Brisbane's suburbs in July 2024 to buy nails, metal pipes and ingredients for explosives, crown prosecutor Sally Flynn told the jury.
"Dollar store closed so I could not get nails," the boy texted a friend.
"I went near the train tracks and tested the flammability of a (gas canister)."
The teen used his iPhone and laptop to search for "where is Peter Dutton located" as part of an alleged plan to use bombings to oppose the Liberal Party's then-policy of building multiple nuclear power stations in Australia.
"Who are you trying to kill?" the teen's friend texted.
"Members of the Liberal Party," the teen replied.
When asked why, the teen responded: "I do not want a nuclear power plant an hour from here."
The teen wrote in a diary about his plans and potentially targeting schools, the jury heard.
"On June 11, 2024 there is an entry ... 'I thought I should target education systems with bombs instead of the Libs'," Ms Flynn said.
The teen appeared to have reconsidered a plan to attack Brisbane's Labour Day march, due to be attended by 20,000 people, as his bomb was not powerful enough, the jury heard.
"I don't know if I will do the bomb and the Labor Day (sic) march," the teen texted a friend.
"It would be better if I had nails as shrapnel."
The teen was inspired by US domestic terrorist Ted Kaczynski, also known as the Unabomber, Ms Flynn said.
The goal of the planned bombing campaign was to bring attention to the argument that humanity was worse off with modern industries and technology, the prosecutor alleged.
The teen allegedly searched for information on the Port Arthur massacre shooter and downloaded a video of the Christchurch mosque shootings that claimed 51 lives.
The friend who exchanged messages with the teen testified they discussed making explosives on texting apps.
Ms Reece asked the friend if he treated the teen's text about bombing the Labor Day march as an "edgy joke".
"Yes, this was our sense of humour," the friend said.
The trial is due to continue for another eight days before Justice Sean Cooper.
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