This is perhaps the most used feature. Imagine you want to design a modern boat hull or a custom lamp shade. You draw the top profile, a middle profile, and a bottom profile. In native SketchUp, you would have to draw lines between these circles and fill them in manually—a tedious process that often results in non-quad faces that look jagged.
For a vintage 2015 setup, Curviloft remains a . curviloft plugin sketchup 2015 66
You mentioned — this likely refers to: This is perhaps the most used feature