Inertial electrostatic confinement fusion devices (fusors) are becoming increasingly attractive neutron sources, and are well suited for global distribution with great humanitarian benefits. However, such neutrons are agnostic to the user’s intent, so could in theory be used for malicious means. This paper discusses the feasibility of using fusors to convert fertile thorium-232 or uranium-238 into fissile material for the purpose of proliferating a nuclear weapon, and whether this is a simple, c