A particular flavor of multi-object spectrographs uses pick-off and steering mirrors. These mirrors perform target selection by relaying the optical beams from variable positions in the focal plane to fixed optics in the instrument. Examples of instrument conceptual designs based on this system are presented and illustrated. Particular emphasis is given to the beam steering mirror (BSM) environment which requires the following mechanical motions: translation, rotations and possibly active deformation of the optical surface. A BSM design featuring translation, tip-tilt and a toroidal deformable surface is presented. First results from a prototype development are also presented. A metrology system including wavefront sensing allows to measure and control the position of the optical beam. This system, required for system tests, integration, calibration and operation, is presented. This work is part of the Laboratoire d'Astrophysique de Marseille (LAM) contribution to the beam manipulation work package of the OPTICON smart focal plane.