This is CADauno, a free open source 3D modeling tool written in C++ and based on OpenGL.
CADauno works with NURBS surfaces. It aims at exploiting the NURBS power at representing free forms, as NURBS are the industry standard for the representation and design of geometry. It's written in C++, based on OpenGL.
This tool provides an interpolation facility ("skinning" technique) which enables the designer to create a closed surface passing through different section curves. So it will be possible, as an example, to build a human body 3D model starting from sections provided by a Computed Axial Tomography scanner.