I think the only real options are: * FreeCAD - Very powerful, very buggy/unstable. * SolveSpace - Very powerful, takes time to understand the interface. * Op

I think the only real options are: * FreeCAD - Very powerful, very buggy/unstable. * SolveSpace - Very powerful, takes time to understand the interface. * OpenSCAD - Great for simpler objects. * Blender - Not very good for CAD modeling, but with non-destructive modifiers and the new Extrude Manifold it can be used. Personally I use Blender all the time for 3D printing. There are some tricks that can help a lot with precise modeling. For example you can draw a plane, but instead of extruding it you can use the solidify modifier to give it thickness. Then the thickness is non destructive. You can also view all edge lengths which help you to check if everything is ok. Since v2.9 you can now use Extrude Manifold which is not precise but works a little like Sketchup making some modeling much easier. And a lot of time my workflow is: Create something in FreeCAD/OpenSCAD -> export to Blender (STL) -> add finishing touches -> 3D print.