The 31-year-old tells the paper that he was able to buy radioactive waste from foreign companies and picked apart the components in a smoke detector (apparently older smoke detector contain nuclear material). He believes he spent between $5,000 and $6,000 on the project in total.
It was only later when the young man contacted Sweden's nuclear power agency that he realized his project was illegal. Police came to his apartment and confiscated the material. The young man was arrested but later released.
It is uncertain how the project went unnoticed, as the man kept a blog about his experiments. Link to story. Link to blog. -via Breakfast Links