This is a quick release nut that I designed for use with my 3D printer spool holder. By depressing the two buttons you can quickly slide the nut to a position along an M8 threaded rod. Then release the buttons and tighten the nut to preference. My application does not call for significant retention force so I have simply printed the threads into the parts. Alternately, I have included a couple of prototype solutions that ought to be more robust. The first is simply to cut a nut in half and insert the halves into the slides and the second uses a couple of small diameter rods as threads.

I am using Slic3r to generate G-code.
SketchUp files are included. 2016-01-24 Update: Cleaned up Sketchup file.