An alternative is Inertial confinement fusion (ICF), in which fusion of nuclei is initiated by heating and compressing a fuel target, typically in the form of a pellet containing deuterium and tritium contained in a device called a hohlraum (hollow space or cavity) using an extremely powerful laser.
Heretofore, design concepts for free-floating space colonies, says Sherwood, have entailed large hollow toroidal spheres with clouds, yards and pastures.