[Duke461]

To summarize the posts on here + give you some of my advice:

• There are non-autodesk and less used autodesk products that work on a mac, such as blender, maya, and rhinoceros.
• However, from what i know about maya, this would have a steeper learning curve.
• I with all my heart advise against blender; personally, i despise that program.
• Rhino isn't terrible, but it could get difficult to make a very precise CAD and Inventor features (chain, stress analysis, etc.) would be non-existent
• Autodesk Inventor will run for free on a Mac; however, you must have a program that can run windows on the mac. Autodesk suggests Parallels Desktop
• Parallels is pretty expensive (60 dollars or 14 day free trial if you speed rush your CAD ), but if you're willing to pay the price, Inventor is the #1 choice
• AutoCAD is free, and runs on a Mac without any middlemen. I know this because i have it on my mac.
• However, as an experienced Inventor CADder, in my opinion, i do not care for AutoCAD too much, and you really can't easily perform as many actions as you could easily do on inventor. I also believe you can't perform actions such as chain and stress analysis on AutoCAD either, as i mentioned above with Rhino

Bottom Line: If you've got 60 bucks, get Inventor.

Hope this helps,
-Duke

Any other questions let me know.