OpenSCAD is an open source programmatic CAD program, making use of Qt for the user interface, CGAL for CSG evaluation, OpenCSG and OpenGL for CSG previews, as well as boost, eigen and glew.
It's focus is not on artistic purposes like Blender, but more on creating 3D models of machine parts.
Other projects, like Libre 3D, were inspired by OpenSCAD.
If you're a programmer OpenSCAD will be familiar, otherwise probably not.
Ranked in these QuestionsQuestion Ranking
Pro Ideal for programmers
Because the 3D-objects will be programmed. You define basic geometric objects, scale, rotate or move them, create unions, intersections, hulls, differences, ...
Pro Text based description
Hence the resulting files can be easily stored/merged in version control systems.
Define some variables and use them in the code.
Pro Easy to use
Con Need to know scripting
Con No measurements from any area
Con SVG exports a single big shape
It should export one shape per object, so it would be re-usable in SVG tools.