Hello, Michael.
Your program is cool, just short of a couple of little things that keep it from being a tool for conceptual artist: 1) patch, when constructed, should have a snug fit to the neighbouring surfaces tangent and curvature. This is necessary for editing and restoration.
2) curves with edges should have copied the same degree as the original from which the copied, also if the surface formed by the curve profile of 5 degrees, which stretched along the Guide, the prjected line on the surface of which must have the same degree, and shaping. In short you need complete control over the geometry, because it is very hard to deal with errors. Offensively, When an artist is forced to conceptual design started at Moi 3d throwing and Rehan in CATIA are all just because of the fact that he needs just a normal form surfaces.
3) should be able to use blend's guides, and be continuous for the tangent and curvature, not only to surfaces of ribs which he builds, but also from the lateral (perpendicular) surfaces, such as patches with support for tangent constraint and curvature to the neighbouring surfaces, only here blend. It is very convenient and correctly, saves a lot of time, not to mention the fact that some surfaces could not be built without it.
4) rounding too raise questions, but their mistakes can be corrected just by yourself manually if the first 2 points will work.
Very nice your program, but it does nothing to be more functional, not worry about adding decent features will make it a little more difficult, it is not, I think artists will thank you if they do not have to alter geometry. Prior to that I've met, that many begin to nurbs modeling with Moi 3d, but after working a bit, pass away to other products, despite the ease and convenience of the program because many need a result. I am sure that if you make a normal control curves and surfaces not only patches on a tangent and curvature, as well as normal operation with degrees of projected curves and forming surfaces, then your product will live long, competitors will be small. Now it is convenient, but it will be even and complete in terms of functionality, so that you do not need to look for another.
P.S. I'm sorry for my English, is Google Translator