The 16-year-old charged with plotting a high school massacre in the South Australian Riverland has been denied bail and remanded in custody.
Earlier, prosecutor Amy Winra opposed the bail application even with strict conditions in the Adelaide Youth Court, saying the teen was "extremely likely" to carry out the attack if released.
Ms Winra said the boy, who can't be identified, and his 18-year-old co-accused plotted to "kill as many people as possible".
She said the pair had attempted to obtain guns and made other weapons which they tested out in October, including a homemade Molotov cocktail and what was referred to as a "poor man's napalm".
They had also made their own body-armour and had machetes and knives.
The boy's defence counsel requested bail with the strictest home-detention monitoring, but Ms Winra said his internet skills and weapon-making ability meant he would be difficult to control.
"Because he has the skills to source and make weapons, he can still make weapons. Your Honour can't stop him from possessing household goods," she said.
The two teens had allegedly been planning a massacre at a school using knives and explosives, but their plot was thwarted when fellow students alerted police.
Police believe there would have been significant casualties if the attack had gone ahead before the end of the school year. It's believed the pair had been planning the attack since June 1.
They would not identify the school in the Riverland area, but said the two had "a relationship" with the school.
The 16-year-old was arrested on November 7 after police searched his home. He has been in custody since then.
He faced court on Tuesday charged with soliciting to kill as well as using or having possession of a prohibited weapon, unlawful possession and dealing in body armour without written permission.
The 18-year-old, whose name is suppressed by a court order to protect the identity of the younger co-accused, was also arrested on November 7 and will appear in Adelaide Magistrates Court in January charged with aggravated counts of threatening to kill.
In court on Tuesday, Magistrate David White said he was concerned about the 16-year-old using a computer, given the crimes he was charged with.
"On the prosecution case, this is sophisticated offending that involves a great deal of planning," he said.
Mr White said he denied bail based on the gravity of the crimes.
The boy will next appear in court at the end of January.