These two plates can be sandwiched either side of a wire rack to hold a commutator and camera.  The spacing of these plates is for the rack that we use ( ), but can easily be modified from the included OpenSCAD files.  We use the ELP 1 megapixel dome USB security camera (Shenzen, China), and the Pinnacle Technologies commutators (Lawrence, KS).  We used short machine screws to join the plates.