Adjustable link

You need to screw things together but need to be able to adjust the distance, here is a solution to that problem.
Customize bolt size, width, length and thickness.
The customiser unfortunately have a bug (it doesn't understand entering the diameter for cylinders, only the radius), a nre version of the same thing can be found here: http://www.thingiverse.com/thing:394679 use that one instead if you want to use the customizer!
Downloading the scad file an using open scad works equally well f