Damon Smith, 20, has been jailed at the Old Bailey for 15 years for planting a home-made bomb on a busy Tube train.
The former altar boy built the device at home with a £2 clock from Tesco after googling an al Qaeda article entitled Make A Bomb In The Kitchen Of Your Mom.
The 20-year-old, who grew up in Newton Abbot, Devon, denied possession of an explosive substance with intent but admitted the lesser offence of making a bomb hoax.
His lawyer told jurors he was no “hate-filled jihadi” and never meant to harm anyone.
But the jury at the Old Bailey rejected his explanation and found Smith guilty of the more serious charge after deliberating for two hours.
On October 20 last year, Smith, who was then 19, headed to his college in Holloway, north London, carrying a rucksack packed with explosives and ball-bearing shrapnel.
CCTV showed him travelling on the Jubilee Line before leaving the bag on the tube as he got off.
Commuters alerted the tube driver to the rucksack, who raised the alarm after spotting wires coming out of it.
Had Smith’s timed bomb worked, it would have exploded as commuters were ordered off the platform, the Old Bailey was told.
After being arrested by counter-terrorism officers, Smith admitted making the bomb but claimed it was meant to be a Halloween joke.
A search of his home revealed an obsession with guns, explosives and other weapons.
A blank-firing self-loading pistol, BB gun, knuckleduster and knife were all recovered from the property.
Analysis showed he had watched YouTube videos on explosions and posted a picture of himself on Facebook in a Guy Fawkes mask holding handcuffs and a knuckleduster.
The jury heard Smith, who has an autism spectrum disorder, was interested in Islam – however he denied being an extremist.
He had exhibited an interested in bomb-making since the age of 10 and said that it was “something to do when he was bored”.