Looking for a simple (free/os) triangle mesh editor

[Philippe Hurbain]

Problem is indeed trade-off between learning curve and capacity... It depends also on the kind of shapes you need. SketchUp might be a good choice (no serious personal experience though). For the simplest shapes that can be created from CSG, studio part editor can be considered and is easy to use. For more complex organic shapes Meshmixer is a capable free sculpting solution.