Best software to start

[LuckyImperial]

I highly recommend OnShape. It's free, intuitive, browser based (don't need a fancy computer or install), and provides tons of tutorials for new users. The only con is that your designs are public. It also provides a great foundating should you choose to move to SolidWorks or AutoDesk Inventor.

[Marm]

I highly recommend OnShape. It's free, intuitive, browser based (don't need a fancy computer or install), and provides tons of tutorials for new users. The only con is that your designs are public. It also provides a great foundating should you choose to move to SolidWorks or AutoDesk Inventor.

Those are two major cons for me, online and public. I have a metered connection, so I try to limit my bandwidth pretty well. If I make a design, I at least want credit for the design, if I choose to release it to the public at all. If you are thinking of making an item for profit at all in the future, having even rough prototypes in the public domain before you file for a patent can qualify as prior art, and negate a patent. Haven't tried the system, but I would hesitate to get good with it and then be forced over to another design suite just to work on for profit stuff.

And if you don't like what the other posters have suggested, there's always Sketchup.