Alternatives. What could replace FlexTools?
Direct substitutes
1001bit ToolsSketchUp tools for simple architectural elements: stairs, openings and construction details.
CleanUp³CleanUp³ is a free SketchUp extension that strips unused geometry, materials and duplicate faces to shrink and tidy large model files.
CurviloftSketchUp plugin to create smooth surfaces and 3D 'skins' by connecting contours. Includes: Loft by Spline, Loft along Path, Skinning. Useful for organic modeling, complex curved surfaces, product design.
Eneroth Face CreatorFree SketchUp extension by Christina Eneroth that automatically generates all possible faces from a selection of edges.
Fredo6 BundleFredo6 Bundle is a collection of over 40 free SketchUp modeling plugins (FredoScale, Curviloft and others), with a couple sold separately.
FredoCornerPaid SketchUp desktop extension that rounds, bevels, subdivides, or chops the corners of 3D shapes. It requires LibFredo6 and SketchUcation ExtensionStore.