Reed Wischhusen, 32, smiles as he tells Avon and Somerset Police officers that his homemade machine gun is his "pride and joy".
Wischhusen had drawn up a "kill-list" of former classmates and others he wanted to target in a chilling 1,700-word document titled “Revenge”.
The Oklahoma bombing of 1995 and the Columbine High School shooting in 1999 were referenced in his four-page document found inside his house on Wick St Lawrence, near Weston-super-Mare, Somerset.
He told the trial he had "hated" all the individuals on the list - but claimed he was too much of a "coward" to carry out what he described as a "fantasy."
Wischhusen will be sentenced in December.