Sketchup Plugin : CURVILOFT v1.2d
Curviloft facilitates sketchup users to extrude diversified 2d profile in plain ol sketchup with its Loft By Spline tool.
This plugin can make surfaces from contour lines. It has the similarity with SketchUp Sandbox. The plugin can easily create caves, pipes, etc. Requires installation of the plugin LibFredo V4.7a.