The court was shown an 18-second video, made by Strang, in which he compared himself to various killers.
In addition, prosecutors said he had accessed various videos on the internet containing “accurate and viable” instructions relating to explosives.
Police found a video, created just minutes before their arrival at his home on 10 September, in which he said he was fine-tuning his gunpowder.
The chemicals had been bought by his mother, thinking they were for a science experiment.
Strang did not have terrorist links, the prosecution stated, but did have a “troubling extremist mindset”.
The court also heard Strang had no previous convictions.
Charles Miskin KC, defending, said Strang had accepted responsibility “for the things that he did do”.
He was 17 years old at the time of the offences, Miskin said, adding that young people often found it difficult to manage their emotional state.
Strang previously said he struggled to express his distress, and this would lead to behaviour that was impulsive.
Miskin went on to say that his interest in serial killers did not come out of the blue, but was a “reaction to real-life events” and that he had no coping mechanism and a personality that was “obsessive”.