Customiser: Thumbwheel with scale (Remix)

This is a first go at a customiser for http://www.thingiverse.com/thing:874155 by jamesarm97, which was derived from http://www.thingiverse.com/thing:844008 by positioning the nut underneath, which in turn is a descendant of http://www.thingiverse.com/thing:225188, by adding knurling.
Variable names remained mostly unchanged, so did their initial values. At this point I only wanted the scad file to load and render, using the customiser. I'm sorry if some parameters don't make huge amount of se