I've noticed the same "squaring" effect when RayDream 5.0 does a torus extrusion: any part of the cross-section close to the sweep path circle is nicely round, but parts further away from the circle start to square off. The problem seems to stem from the fact that the circular sweep path is only created with four points. Here's a work-around: On the circular sweep path, add points at the 45 degree positions. This smooths out the extrusion further away from the sweep path. Repeat and add points at 22 degree positions around the circle for even more smoothness, etc. See image for an illustration of the steps (RayDream 5, sorry no shader...) Hope this helps!