Hi Tom, 
re: 
> The slider function is a nice enhancement, but why does 
> the slider-script only display half a circle ? Is there an 
> explanation how to use it correctly ?
 
Brian mentions something about that here:
 http://moi3d.com/forum/index.php?webtag=MOI&msg=5616.9
It sounds like the slider version makes a half circle because it was for making profile curves for a 2 rail sweep with the endpoints on rail curves.
 
If you want to make a flat one and not one between 2 rail curves, probably use the SuperEllipse version instead.
 
   - Michael  
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