Then what do you call this? Lofted from open curves, that is, splines. Rhino calls this loft, just like those closed splines. You cannot use both types together. To confuse the matter further, there's an action called From Network Curves, where you have to have 3 curves in one direction (U) and 3 in the other (V). There's also Patch, where you can use both open and closed curves. Finally, there's the abovementioned pipe, where you need just the path curve and the program creates a pipe around it, according to the radius. I can create a tube by using Pipe around a curve, by sweeping a circle around a curve and by arranging circles around an _imaginary_ path curve for loft. :-) Apropos Johnny-come-lately, it's interesting that Cinema uses the same meaning for Sweep. And IIRC, it's not that young, regardless of not being as widely used as Max. BTW, anybody remembers an old 3D program called Lathe? Couldn't do anything except, surprisingly :-), lathing.

-- erlik