Spiderbot:Cable Suspended 3-D Printer

In exemplary implementations of this invention, an actuated fabricator deposits structural elements (e.g., tensile structural elements) in a 3D pattern over large displacements. The fabricator is supported by at least three elongated support members. It includes onboard actuators that translate the fabricator relative to the ends of the support members. The fabricator is configured, by actuating different translations along different support members, to translate itself throughout a 3D volume. In some implementations, each of the actuators use fusible material to fuse metal tapes together, edge-to-edge, to form a hollow structure that can be shortened or lengthened.