A manipulator arm module includes a hollow spool with corresponding top and bottom spool ends. An upper envelope member has a bottom ring rotatably attached to the top spool end, a top ring oriented at an angle to the bottom ring, and struts rigidly connecting the rings. A top drive rotates the bottom ring with respect to the spool. A manipulator arm comprises a plurality of modules the bottom spool end of one module rotatably attached to the top ring of a next lower adjacent module. Each ring is rotationally driven independently. A stabilizer is connected between adjacent spools and allows the adjacent spools to move closer together or farther apart, and resists relative rotative movement of the adjacent spools.