Customizable Printable Spool for Filaments

This is a customizable filament spool which can be easily printed, even with small printers. It is a remix of the great design [#7980 by MakeALot](https://www.thingiverse.com/thing:7980), see also the related [thing #102270 by ksaathoff](https://www.thingiverse.com/thing:102270) with variable width.
This design uses a very similar geometry but offers several cutomizable options and additional features.

###Customizer:
Note: this design does not work properly in Makerbot's Customizer on Thingiverse (why?\*). Use the integrated customizer in OpenSCAD instead (see [thing #2815234](https://www.thingiverse.com/thing:2815234) for screenshots):

* Download “spool.scad” and “spool.json” from “Thing Files” and copy them into the same folder.
* Get the newest OpenSCAD version here: http://www.openscad.org/downloads.html
Version should be at least 2018.x, so you may need to scroll down to “Development Snapshots”. This thing was tested with version 2018.09.05.
* Launch spool.scad in Open