I understand that neutron stars arise because of gravitational forces in a collapsing star. But consider an isolated free neutron moving at slow speed. Leaving aside its decay (12m half life), can they be "contained"? If two of them came together, would the strong nuclear force bind them? Is there any reason why you could not contain a small "cloud" of free neutrons? You cannot do so electromagnetically, but what if you built a container from atoms that do not interact with free neutrons? If you contained a cloud of free neutrons, could you cool it to a liquid or a solid? Unlike a neutron star, which was already extremely massive and compressed before the protons and electrons were squeezed together, could a solid chunk of free neutrons be contained at normal pressures?