Parametric spool bearing bushing

This is my first thing, so it is pretty primitive. I couldn't find the right bushing for my ABS spool (inner diameter 52.5 mm) and standard 608 bearings, so I created parametric part in OpenSCAD. Now you can modify both diameters (inner and outer) of the bushing very easily in the beginning of the OpenSCAD file.

The generated STL file is for 52.5 mm (spool)/22 mm (bearing).

The shape of inner and outer diameter is not cylindrical but octagonal for the higher flexibility to insert the bea