Enriched uranium is hard to acquire but it's not hard to make if you have a source of thermal neutrons. You can get thermal neutrons in a number of ways. I'm

Enriched uranium is hard to acquire but it's not hard to make if you have a source of thermal neutrons. You can get thermal neutrons in a number of ways. I'm not going to get into the details, but establishing criticality is not easy, but it's not hard either, at least if you're not concerned with safety.