Zahid Iqbal, 31, and Mohammed Sharfaraz Ahmed, 25, were sentenced to 16 years and three months in prison today after admitting terror charges.
London's Woolwich Crown Court heard that the pair discussed sending a remote-controlled toy car carrying a home-made bomb under the gates of a Territorial Army centre in Luton.
Mr Justice Wilkie QC said they posed "a significant risk of serious harm to the public" as he imposed a custodial sentence of least 11 years and three months, with a five-year extension period subject to licence.
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The Metropolitan Police Federation, which set up the official JustGiving site, said it felt a "suitable amount" had been collected.
There is no evidence the Westminster attacker Khalid Masood was associated with so-called Islamic State or al Qaeda, the Met Police said.
Janet Ajao said in a statement: "I do not condone his actions nor support the beliefs he held that led to him committing this atrocity."