Some wood, aluminum angle channel and roller bearings is what makes up majority of the camera slide that was designed by Making Stuff. There is a lot of precision that is needed to allow the unit to slide smoothly. Even though much of the design is cut by hand using a table saw and screwed together with a handful of drywall screws it works really well. A stepper motor and pulley position the truck along the rail to move the camera where it is needed.
Thanks for the tip Bill.