JStephen is right, however I assumed that you already owned AutoDesk products by lookin at the first thread. If you don't own either Inventor or SolidWorks don't bother.
But you can look in google for CAD open source and you might find Solid Modeling Software free. Also there are other options...
I used to have a student that work designing furniture. You might want to explore either Inventor or SolidWorks. They are more useful to create 3D Models, also you can create working drawings from these models.
If you are proficient in AutoCAD I recommend Inventor.
Ian Falu, P.E...
You can learn any software by basically going through a good book and other resources. However participating in a structured class allows you to concentrate in the areas that are more relevant to your job.
Also you will have a guide that can walk you through your problems.
Ian Falu, P.E...