A student who sent packages with improvised explosive devices through the post as part of a plot to get fraudulent refunds has been jailed.
Ovidijus Margelis, from Cambridge, sent the packages to depots around the UK, causing evacuations, road closures and disruption to more than 50,000 people.
He was jailed for 21 months at Kingston Crown Court after admitting making explosive substances and fraud charges.
Judge Martyn Barklem said Margelis had been "incredibly stupid".
The court heard Margelis placed the improvised explosive devices inside packages, and they were made to burn through address labels meaning they could not be delivered.
This meant vendors such as Amazon and PayPal would provide a refund, leaving Margelis "with the goods and refund".
Edward Franklin, prosecuting, said Margelis' actions were "reckless in the extreme" and had caused "considerable disruption".
The court heard the economic cost of his actions was just under £600,000.
Mr Franklin said that on one occasion, on 6 September, an army bomb disposal team had to be called to the Dunfermline depot in Fife.
Another incident, five days later, saw Avon and Somerset Police shut parts of the A38, while cordons were placed around post offices in Bath and Bristol.
Margelis was arrested by armed police in Cambridge the same month following reports of a suspicious package in Cricklewood, north London.
Tom Wainwright, for Margelis, said his client lacked "common sense" and "foresight" and his actions had been "incredibly stupid, but not malicious".
In February, the third-year business management student at Anglia Ruskin University pleaded guilty to making explosive substances, fraud by false representation and possession of an article for use in fraud.
Sentencing Margelis, Judge Martyn Barklem said police would not have been aware of his intentions.
"Incredibly stupid but not malicious was [Mr Wainwright's] characterisation, with which I concur," he added.