Rhino

“Rhino can create, edit, analyze, document, render, animate, and translate NURBS* curves, surfaces, and solids, point clouds, and polygon meshes. There are no limits on complexity, degree, or size beyond those of your hardware. ”
– from the Features page on the official Rhino site

“NURBS, Non-Uniform Rational B-Splines, are mathematical representations of 3‑D geometry that can accurately describe any shape from a simple 2‑D line, circle, arc, or curve to the most complex 3‑D organic free-form surface or solid. Because of their flexibility and accuracy, NURBS models can be used in any process from illustration and animation to manufacturing.”
– from the Nurbs page on the official Rhino site
 

Tutorials