Sound system SEOS waveguide modeling...help please

Hello all I’m hitting the forum running…
I’m a Sound system designer and Speaker builder and I’m looking for pointers on how to model this SEOS Waveguide.
It would be very simple to model without the curves as it’s essentially a rectangluar pyramid shape with curved corners and transitions…
I’m looking for recommendations for a method to draw it, some kind of extrusion plugin or something to smooth the angles after drawing it.
It don’t need to model it exactly I just need a visual representation.

http://horns-diy.pl/horns/seos/seos-15/

For that sort of thing I would look at Thomthoms SUbD and Vertex tools, not free but well worth the price.
Subd

Wow! That looks ideal…thanks a mill!