If you have a heavy camera (or lens), you will probably want to increase the value of foot_spacing (look in camera_slide_end.scad).

Print 1x slide and 2x end
Add 4x LME8UU linear bearings to the carriage
Use a 1/4 inch screw to attach a camera (or quick release plate) to the carriage
Push 2x 8mm diameter rods through the bearings
Push or hammer the ends on the rods