A hub joint includes a metal rod and pin for joining tubular members in three-dimensional space for assembling a frame structure. The hub joint enables rapid assembly, rapid reconfiguration, and rapid disassembly without using any specialized tools. Multiple hub joints may be used to form geodesic domes, freestanding trusses, space frame slabs, tetrahedrons, and pentahedrons. The hub joints allow different frame configurations that are lightweight, strong, durable, scalable, expandable, and portable.