The boy, who cannot be named due to his age, spent last week on trial in Brisbane Supreme Court after pleading not guilty to one count of acts done in preparation for or planning a terrorist act.
He was accused of researching and testing homemade explosives to attack members of the Liberal Party and a public place.
His alleged targets included then-opposition leader Peter Dutton and Brisbane's Labour Day march.
The teen engaged in "clearly dangerous experimentation" with household chemicals, defence barrister Laura Reece told the jury on Monday during her closing statement.
The central issue at trial was the teen's state of mind or intention at the time of these acts, Ms Reece said.
"He was a troubled kid. He was experimenting not only with explosives but with ideas and beliefs," she said.
"He was seeking out extremist material from wildly contradictory sources from the dark corners of the internet."
The boy was about to turn 16 when he texted a school friend in July 2024 about bombing the Liberal Party over its support for nuclear power and filmed himself testing incendiary devices in his backyard, the jury had heard.
The teenager was serious when he wrote of copying US domestic terrorists like Ted Kaczynski, the anti-technology "Unabomber" and Timothy McVeigh, who killed 167 people with a truck bomb in Oklahoma City, crown prosecutor Sally Flynn told the jury.
"Technology has left a very clear indication of his acts and a very clear indication of his thoughts," she said.
"There is a very powerful body of evidence in that case that comes directly from the defendant. It's his messages that are relied upon, his web searches and the documents he downloaded."
Ms Flynn also said the teen's state of mind was a key issue at trial and pointed to him possessing a terrorist bomb manual, a military handbook on improvised munitions and a video of the Christchurch shooting massacre.
He could be convicted despite no terror attack having occurred, the jury was told.
Ms Reece told the jury the teen's talk of bombing the Labour Day march was an "edgy joke" and on the day of the event he instead stayed at home and chatted to his friend about accounting homework.
The teen's parents had started separating just before his alleged offences and his whole world was coming apart, the jury heard.
"He wrote in his diary he was suicidal and heard voices," Ms Reece said.
Justice Sean Cooper is due to give directions to jurors on Tuesday before they begin deliberations.
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