A universal apparatus is presented, designed to precisely generate a controlled state of mechanical stress upon any kind of optical fiber waveguide. With only minor procedural modifications, hydrostatic or radial pressure (up to about 300 MPa) can be generated, as well as an axial elongation up to 2000 microstrain and a twist up to about 50 full turns. A combination of any two of these types of stresses, such as twist under hydrostatic pressure, can also be generated to satisfy a specific need for a particular experiment. The apparatus provides a unique possibility to experimentally investigate several nontrivial effects associated with propagation of light through a waveguide remaining under a controlled stress environment. An example of such an application related to polarization coupling in highly birefringent fibers is also discussed.