He had papers relating to the Oklahoma bomb massacre, in which he had a "macabre interest", said prosecutor Geoffrey Mercer. The boy, from the St Blazey area of Cornwall, was sentenced, having pleaded guilty at an earlier hearing to two charges of making an explosive substance and to possessing a prohibited weapon.
He also asked for two other offences, of making an explosive substance, and stealing chemicals, to be taken into consideration. Judge Graham Cottle told the boy: "It is clear from the evidence in this case you have developed a very disturbing obsession with explosives. It is clear at this stage the risk of your reoffending is very high, making it unsafe and wrong to pass a sentence which allows you, at the moment, your liberty."
Mr Mercer said that on 22 July the boy was given a 12-month conditional discharge for setting off a small explosive device outside a nightclub in St Austell. Four days later he set off "a homemade bomb in a biscuit tin" on wasteground near homes in Par. A resident said a loud bang "shook the house", which was 15 yards away. There were flames two or three feet high and shrapnel landed in a garden, said Mr Mercer.
The teenager set off another device in Par on 3 August and six days later went voluntarily to the police with his mother, the court was told. Chemicals which could be used to make explosives were taken from his bedroom and destroyed. He told the police he learnt about explosives from school chemistry lessons, and by experimenting.
He "perfected" explosive devices and told the police he had set off four others. The boy also said he had told other youngsters how to make explosives, said Mr Mercer. While on bail, he was stopped by police in Lostwithiel on 16 October, carrying a small bag. He said it contained a bomb which he was going to sell to a man.
An "improvised shotgun" was also found on the boy, said Mr Mercer. A Royal Navy team was called to make the device safe. At the boy's home items for making explosives were found, said Mr Mercer, who added: "One of the drawers in his bedroom was booby-trapped, with an explosive device fitted to it." The teenager told police the device he had been carrying could "shake a few windows" in the right conditions. He said the booby- trap in the drawer would have caused a small explosion if it had gone off. He collected shrapnel from his devices to see how far they had gone and had tried to make a Semtex substitute, but never found a formula.
Counsel for the defence, Barry van den Berg, said the boy was 14 when he started to "dabble in explosives". He was lonely and had been rebelling for a long time against authority. His actions gave him a "notoriety" among friends, which for him was "heady stuff". He had used his intelligence in a "destructive way", said counsel.
A psychiatrist, Georgina Redding, said the boy, who suffered from a conduct disorder and mood swings, got "a buzz" and "feeling of omnipotence" from what he did. There was a "mismatch" between the boy and his parents, who were in a strict religious sect.
The boy's father told the court his son became "haughty and disobedient" and had taken on the "destructive side" of science.
He said they were a close family but admitted losing parental control in the summer of last year.