When it comes to 2D CAD/CAM, then QCad is the best. They have a GPL version, but their commercial version has a lot more features, like importing/exporting most Autocad files, and CAM functionality. For just $40 bucks, it’s worth every penny. The only disadvantage it has is that it can’t ever have an ARM version, because the plugin they use for Autocad files is licensed, and it only exists for x86 afaik.