If you use any of the following "heavyweight" SketchUp tools, you must have LibFredo6 installed:
Think of LibFredo6 as the "operating system" for Fredo6’s suite of tools. It contains the shared code, functions, and commands that other plugins call upon to function. Without this library installed, popular extensions like Curviloft or FredoSpline would fail to load. libfredo6 v3.2 for sketchup