Rich Felker@landley @ErosBlog OpenSCAD (use latest git not last tag, it's a ton faster & more reliable) if you like text based human editable version controllable model source that feels like coding.
Blender for editing existing meshes or doing non CAD like modelling.
FreeCAD maybe as a sub for OpenSCAD if you want more of a real CAD like model with features like chamfers.
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