There are several good 3D CAD systems that you can use for free
1) FreeCAD. ?This runs on Mac, Linux and Windows. ?It is 100% free and Open Source www.freecad.org
2) Fusion360 is free for personal use but has some limitations but those don¡¯t matter for most people as we don¡¯t own 5-axis CNC machines. ?It also can be run on Mac, Linux (with the help of a virtual machine) or Windows https://www.autodesk.com/products/fusion-360/personal
3) OnShape is free but in the free version your files are readable by everyone.?https://www.onshape.com/en/pricing. OnShape runs on any computer that can run a web browser.
Those are the ones that are free and have a full set of professional features. ?Fusion360 and FreeCAD can do some CAM too and generate g-code for machine tools should you ever get into that. ?Even with limited feature sets, these are all capable of a project as complex as (say) an industrial robot.
To get back on-topic¡
Here is an example of the kind of work you can do. with the above (either of them). This is a VIEW-ONLY link to a 7x12 Mini Lathe. ? Play with the viewer controls and rotate it with the ¡°orbit¡± tool ?and ¡°explode¡± it. ?Again, most of us will never design a machine this complex, but it is nice to know the tools will never be the bottleneck?
