What is the quickest way to double your money beside playing stocks?

How long does it take for a smart investor to become a millionaire starting out with just $1000?

The stock exchange is just gambling, you're as likely to lose the lot as you are to make a profit. With a small amount of cash buying and selling things for a profit will make you money more quickly, well it will so long as you know what you're buying and know that it will sell for more.