My only guess would be that you could implement your own BezTube class and make it display not only tubes but anything you like... the trick is that first you should be able to determine the direction vector of how the curve 'flows' in each of the points on it you locate. Then, draw vertices around this point in a circle which normal vector is co-aligned with the direction vector.

Thanks, Karsten. This should be quite useful. :)

It seems to me that you want to be able to alter the diameter of the BezTube along its length and this is possible but it does involve some OO programming.

You can create your own class that implements the I_RadiusGen interface your class must have three methods

    public float radius(float t);
   
    public boolean hasConstantRadius();
   
    Object getController();

The first method defines the radius based on the parametric value of t (which goes from 0-1) - you can code this anyway you like.
The second method should return true if the BezTube has constant radius along its length else return false
and the last method getController() should just return null for the moment.

The TubeRadius class is an example which uses an array of floats to define the radius at any point along the curve based on interpolation between array elements to give the radius for any point t >=0 and <=1

Once you have this class you can create an object of that type and pass it to the setRadius method of BezTube. The getBez() method of BezTube returns a reference to the Bezier3D object that defines the BezTube. The Bezier3D class has several methods to return points along the tube as well as normals and tangents.